Question 45 by 8kebkY


									Renal PREP Questions 2007 and 2008                                     across the chest, abdomen, and pelvis as well as bright red blood
                                                                       from the urethral meatus and a deformity of the left femur.
Question 45 You are examining a 5-year-old girl who always has         Among the initial major interventions are insertion of an
had significant daytime wetting and a history of recurrent urinary     endotracheal tube and establishment of two large-bore
tract infections. Findings on physical examination are normal          intravenous lines. Of the following, the MOST appropriate next
except for the presence of a sacral dimple above the gluteal cleft.    step is to
Her urinalysis reveals a specific gravity of 1.005, pH of 5.5, no      A. administer broad-spectrum antibiotics to treat his
blood, no protein, and no white or red blood cells. Magnetic           contaminated wounds
resonance imaging of the spine reveals spinal dysraphism. Of the       B. administer tetanus toxoid
following, the MOST important next step to determine the cause         C. obtain upright abdominal films to assess for ruptured viscus
of this child's primary enuresis is to obtain                          D. order contrast-enhanced magnetic resonance imaging of his
A. abdominal computed tomography scan                                  head
B. abdominal radiography                                               E. place a Foley catheter into his bladder to monitor urine output
C. abdominal ultrasonography
D. renal biopsy                                                        Question 117 A 4-year-old boy presents for a health supervision
E. urine culture                                                       visit, and in the course of the visit, his mother discloses that ever
                                                                       since the birth of his 2-month-old sister, the boy has resumed
Question 77 You are evaluating a 7-year-old boy for hematuria          bedwetting, which had ceased to be a regular occurrence. He is
and proteinuria. As part of the evaluation, you measure serum          dry during the day and has no stool incontinence. Past medical
electrolytes. The serum creatinine is 1.1 mg/dL (97.2 mcmol/L).        history reveals that the child has never been hospitalized, had a
Of the following, the MOST accurate serum creatinine                   negative urine culture at age 9 months associated with a fever,
measurements for children of normal physical development are           and was toilet trained completely at age 3, with only episodic
A. 3 months old (mg/dL) [mcmol/L]: 0.3 (26.5); 2 years old             bedwetting about once every month. Physical examination reveals
(mg/dL) [mcmol/L]: 0.4 (35.4); 7 years old (mg/dL) [mcmol/L]:          a happy, playful child whose growth and developmental
1.0 (88.4); 17 years old (mg/dL) [mcmol/L]: 1.0 (88.4)                 parameters are normal for age and who has a circumcised penis
B. 3 months old (mg/dL) [mcmol/L]: 0.6 (53.0); 2 years old             and normal findings on scrotal examination. Urinalysis of a
(mg/dL) [mcmol/L]: 0.8 (70.7); 7 years old (mg/dL) [mcmol/L]:          specimen obtained via clean catch urination shows normal results.
1.0 (88.4); 17 years old (mg/dL) [mcmol/L]: 1.2 (106.1)                Of the following, the next BEST step in the management of this
C. 3 months old (mg/dL) [mcmol/L]: 0.3 (26.5); 2 years old             boy is to
(mg/dL) [mcmol/L]: 0.4 (35.4); 7 years old (mg/dL) [mcmol/L]:          A. begin imipramine therapy at bedtime
0.6 (53.1); 17 years old (mg/dL) [mcmol/L]: 0.9 (79.6)                 B. obtain urine for culture and sensitivity
D. 3 months old (mg/dL) [mcmol/L]: 0.6 (53.0); 2 years old             C. perform renal ultrasonography
(mg/dL) [mcmol/L]: 0.4 (35.4); 7 years old (mg/dL) [mcmol/L]:          D. reassure the mother that this is most likely a temporary
0.7(61.9); 17 years old (mg/dL) [mcmol/L]: 0.7 (61.9)                  regression
E. 3 months old (mg/dL) [mcmol/L]: 0.7 (61.9); 2 years old             E. refer the boy for voiding cystourethrography
(mg/dL) [mcmol/L]: 0.8 (70.7); 7 years old (mg/dL) [mcmol/L]:
0.7 (61.9); 17 years old (mg/dL) [mcmol/L]: 0.7 (61.9)                 Question 125 You are asked to evaluate a 15-year-old boy who
                                                                       presented to the emergency department with gross hematuria
Question 93 You have been the primary practitioner for a 15-           that began the day before. He ran his first marathon yesterday.
year-old girl since she was 3 years old. She never has been            He reports no dysuria, urgency, frequency, or abdominal or flank
hospitalized, and her history, vital signs, and physical examination   pain. His vital signs and physical examination findings are normal.
findings on this health supervision visit are normal. At each of the   Urinalysis reveals: specific gravity, 1.010; pH, 6.0; large blood;
past two yearly visits, urinalysis revealed no abnormalities except    no protein; 0 to 2 red blood cells; and 0 to 2 white blood cells. A
2+ protein. Her urinalysis today again reveals 2+ protein with no      serum creatinine is 2.7 mg/dL (238.7 mcmol/L). His complete
other abnormalities. Her complete blood count, measurements of         blood count is normal. Of the following, the MOST likely cause of
serum electrolytes and serum complements, and antinuclear              his hematuria and renal failure is
antibody test results are all normal. Two successive 24-hour urine     A. hemoglobinuria
collections reveal 321 and 387 mg protein. You now refer the girl      B. immunoglobulin A nephropathy
to a pediatric nephrologist. Of the following, the MOST important      C. myoglobinuria
next step for the pediatric nephrologist is to                         D. urinary tract obstruction
A. obtain a first morning urine specimen                               E. urolithiasis
B. obtain renal ultrasonography
C. perform a renal biopsy                                              Question 141 You are seeing a newborn boy for the first time.
D. repeat the 24-hour urine collection                                 Several prenatal ultrasonographic examinations revealed bilateral
E. repeat the urinalysis                                               hydronephrosis. The boy's weight and height are appropriate for
                                                                       gestation, and his physical examination findings are
Question 109 An 11-year-old Caucasian boy who has no                   unremarkable. Postnatal ultrasonography reveals severe bilateral
significant past medical history presents to the emergency             hydronephrosis. Of the following, the MOST likely cause of the
department with a 3-day history of brown urine. He reports no          hydronephrosis is
dysuria, urgency, frequency, or abdominal or flank pain. His vital     A. polycystic kidney disease
signs reveal: temperature, 99°F (37.2°C); blood pressure, 141/84       B. posterior urethral valves
mm Hg; heart rate, 92 beats/min; and respiratory rate, 24              C. ureteropelvic junction obstruction
breaths/min. Significant findings on physical examination include      D. vesicoureteral reflux
moderate periorbital and leg edema. His urinalysis reveals             E. Wilms tumor
moderate blood and 4+ protein. The serum complement 3 (C3)
and C4 concentrations are both low. Of the following, the MOST         Question 147 You are evaluating a very low-birthweight (VLBW)
likely cause of his hematuria is                                       preterm infant who experienced polyuria in the first 72 hours after
A. immunoglobulin A nephropathy                                        birth. No diuretics have been prescribed, and there is no
B. membranoproliferative glomerulonephritis                            glycosuria, hematuria, or obvious anasarca on examination. You
C. postinfectious acute glomerulonephritis                             collect a urine sample to measure electrolytes and creatinine and
D. urinary tract infection                                             simultaneously obtain a blood sample to measure serum
E. urolithiasis                                                        electrolytes and creatinine. Of the following, the MOST correct
                                                                       statement regarding sodium handling in the VLBW infant is that
Question 112 An 11-year-old child is brought to the emergency          A. fractional excretion of sodium is lower than in term infants
department with massive trauma after a motor vehicle crash. His        B. intravenous sodium supplementation is necessary from birth
Glasgow Coma Scale score is 3. Rapid assessment reveals marked         C. phototherapy increases sodium requirements
bruising of the face and blood from the mouth, nose, and ears. In      D. sodium excretion increases with gestational age
addition, the child has large areas of bruising and abrasions          E. water losses generally exceed sodium losses
                                                                        B. congenital nephrotic syndrome
Question 157                                                            C. congenital Wilms tumor
You are evaluating a newborn boy who has lax abdominal                  D. oligohydramnios sequence
musculature (Item Q157A) and bilateral undescended testes.              E. Turner syndrome
Other findings on physical examination are normal. Of the
following, the MOST likely urologic abnormality in this boy is          Question 189 You are seeing a 10-year-old boy and his 13-year-
                                                                        old sister for the first time. When you review the medical records
                                                                        provided by their mother, you find normal medical histories, vital
                                                                        signs, and physical examination results for the children. However,
                                                                        the family history indicates that two of the children's uncles are
                                                                        receiving hemodialysis and are deaf and one grandfather died of
                                                                        kidney disease. You obtain a screening urinalysis (UA) in both
                                                                        children. The boy's UA reveals moderate blood, negative protein,
                                                                        and 20 to 30 red blood cells/high/power field (RBC/hpf); the girl's
                                                                        UA reveals trace blood with 5 to 10 RBC/hpf. Of the following, the
                                                                        MOST accurate statement regarding the prognosis for these
                                                                        children is that
                                                                        A. the boy will develop end-stage renal disease (ESRD); the girl
                                                                        will not develop ESRD
A. hydronephrosis
                                                                        B. the chances of developing ESRD are equal in the boy and girl
B. renal cysts
                                                                        C. the boy will develop ESRD with hearing deficits; the girl will not
C. ureterocele
                                                                        develop ESRD
D. ureteropelvic junction obstruction
                                                                        D. the boy will develop ESRD and esophageal leiomyomatosis; the
E. vesicoureteral reflux
                                                                        girl will develop only hearing deficits
                                                                        E. the boy will develop ESRD and giant cell thrombocytosis; the
Question 163 You are present at the birth of an infant in whom
                                                                        girl will develop only ESRD
bilateral hydronephrosis was diagnosed in utero. A fetal shunt was
placed in each flank between the renal pelvis and the amniotic
                                                                        Question 195 You are called to evaluate a male infant at 50
cavity. Nonetheless, the infant has bilaterally palpable flank
                                                                        hours of age because he has not voided. He was born at term and
masses, and the shunts are not apparent at birth. The infant
                                                                        has breastfed poorly, but has passed stool. He appears
shows no dysmorphisms and has no respiratory distress. Renal
                                                                        uncomfortable on physical examination, with a large abdomen
ultrasonography reveals bilateral hydronephrosis. Of the
                                                                        and seemingly palpable bladder. There is no respiratory distress.
following, the MOST correct statement regarding the
                                                                        The external genitalia are normal, and both testes descended. Of
fetus/neonate who has obstructive uropathy is that
                                                                        the following, the MOST appropriate initial step in this infant's
A. urinary tract infection, hydronephrosis, and respiratory distress
                                                                        evaluation is
all can be treated and resolved with a fetal shunt
                                                                        A. consultation with a urologist
B. urinary tract infection, hydronephrosis, and respiratory distress
                                                                        B. intravenous pyelography
typically lead to fetal or neonatal death
                                                                        C. nuclear renal scan
C. urinary tract infection is common, hydronephrosis often
                                                                        D. passing of a urinary catheter
persists, and respiratory distress is not uncommon
                                                                        E. renal ultrasonography
D. urinary tract infection is uncommon, hydronephrosis resolves
spontaneously, and respiratory distress is uncommon
                                                                        Question 205 A 10-year-old girl presents to the emergency
E. urinary tract infection is uncommon, hydronephrosis resolves
                                                                        department with a 1-day history of brown urine. She reports no
spontaneously, and respiratory distress results from apnea
                                                                        dysuria, urgency, frequency, or abdominal or flank pain. Her vital
                                                                        signs include: temperature, 98.8°F (37.1°C); blood pressure,
Question 173 You are evaluating a 10-year-old boy who has
                                                                        165/97 mm Hg; heart rate, 84 beats/min; and respiratory rate,
intermittent urinary incontinence. Voiding cystourethrography
                                                                        20 breaths/min. On physical examination, moderate periorbital
detects a urethral stricture. Of the following, the MOST likely
                                                                        edema is evident, but there are no other abnormalities. Urinalysis
cause of this boy's urethral stricture is
                                                                        reveals moderate blood and 4+ protein. The serum complement 3
A. carcinoma
                                                                        (C3) concentration is low, and the C4 concentration is normal. Of
B. chronic infection
                                                                        the following, the MOST likely cause of this girl's hematuria is
C. congenital narrowing
                                                                        A. focal segmental glomerulosclerosis
D. intermittent urolithiasis
                                                                        B. immunoglobulin A nephropathy
E. trauma
                                                                        C. lupus nephritis
                                                                        D. membranoproliferative glomerulonephritis
Question 179 An infant is born following a pregnancy
                                                                        E. postinfectious acute glomerulonephritis
complicated by no prenatal care and reduced fundal height for
gestation on examination during labor. Fetal heart rate tracings
                                                                        Question 221 A 14-year-old boy presents to the emergency
are nonreassuring. Physical examination of the infant reveals a
                                                                        department with a 2-week history of bilateral leg edema and a 3-
birthweight of 1,800 g, flattened facies (Item Q179A), low-set
                                                                        day history of abdominal swelling. His vital signs are:
ears, respiratory distress, a large flank mass on the left, and joint
                                                                        temperature, 98.4°F (36.9°C); blood pressure, 125/67 mm Hg;
contractures. Renal ultrasonography documents a single left
                                                                        heart rate, 84 beats/min; and respiratory rate, 20 breaths/min.
multicystic and dysplastic kidney; the right kidney is absent. Of
                                                                        Physical examination shows moderate ascites and 2+ leg edema.
the following, the BEST explanation for these findings is
                                                                        His urinalysis reveals negative blood and 4+ protein. Serum
                                                                        complement concentrations are ordered and found to be normal.
                                                                        Of the following, the MOST likely cause of his edema and
                                                                        proteinuria is
                                                                        A. immunoglobulin A nephropathy
                                                                        B. lupus nephritis
                                                                        C. membranous nephropathy
                                                                        D. membranoproliferative glomerulonephritis
                                                                        E. postinfectious acute glomerulonephritis

                                                                        Question 222 A 3-year-old boy who has spina bifida has a
                                                                        history of recurrent urinary tract infections (UTIs). He is currently
                                                                        being treated for a UTI. Monitoring laboratory evaluation shows a
                                                                        blood urea nitrogen of 23 mg/dL (8.2 mmol/L) and a creatinine
                                                                        concentration of 1.1 mg/dL (97.2 mcmol/L). Of the following, the
A. Alport disease
class of antibiotics that is MOST commonly associated with renal      of choking. The mother reports that the boy was seen by the
toxicity is                                                           nephrologist 1 week ago, and because of worsening renal
A. aminoglycosides                                                    function, he was begun on sodium bicarbonate. Of the following,
B. azalides                                                           the electrolyte abnormality that BEST explains his current
C. carbapenems                                                        symptoms is
D. cephalosporins                                                     A. hyperkalemia
E. penicillins                                                        B. hypermagnesemia
                                                                      C. hypocalcemia
Question 237 A 12-year-old African-American girl presents to          D. hyponatremia
your office with a 2-day history of gross hematuria. She describes    E. hypophosphatemia
the urine as brown. She states that she has had an upper
respiratory tract infection for about 3 days. She denies dysuria,     Question 78 During your evaluation of a 16-year-old boy at his
urgency, or frequency. Her vital signs and physical examination       health supervision visit, he reports that he had an episode of cola-
findings are normal. Urinalysis reveals: specific gravity, 1.025;     colored urine associated with an upper respiratory tract infection
pH, 6.5; large blood; no protein; too numerous-to-count red           6 weeks ago. The only significant finding on his medical history is
blood cells; and 0 to 2 white blood cells. Serum electrolyte          mild hearing loss. Today his blood pressure is 112/66 mm Hg.
concentrations are normal. Of the following, the MOST likely          Urinalysis shows 3+ blood, 2+ protein, and 20 to 50 red blood
cause of her gross hematuria is                                       cells per high-power field (RBC/HPF). Other laboratory findings
A. focal segmental glomerulosclerosis                                 include: Blood urea nitrogen, 14 mg/dL (5 mmol/L), Serum
B. immunoglobulin A nephropathy                                       creatinine, 0.7 mg/dL (61.9 mcmol/L), Albumin, 4 g/dL (40 g/L)
C. lupus nephritis                                                    Serum complement components (C3 and C4) are normal, and
D. membranoproliferative glomerulonephritis                           antinuclear antibody titers are negative. You discuss these results
E. papillary necrosis                                                 with his mother, who then tells you that she recalls being told she
                                                                      had blood in her urine. Urinalysis for the child's mother
Question 253 A 3-month-old boy is admitted to the hospital for        demonstrates 2+ blood with 10 to 20 RBC/HPF. Of the following,
evaluation of failure to thrive. His birthweight was at the 50th      a TRUE statement about this patient's disorder is that
percentile and length at the 75th percentile. Currently, his weight   A. boys who have this condition are more likely to develop chronic
is below the 5th percentile and length is at the 25th percentile.     renal failure than are girls
His vital signs and physical examination results are otherwise        B. immune complex deposition within the kidney is believed to be
normal. He appears well hydrated. Measurement of serum                causative
electrolytes reveals: sodium, 139 mEq/L (139 mmol/L);                 C. it is classified as a small vessel vasculitis
potassium, 4.7 mEq/L (4.7 mmol/L); chloride, 114 mEq/L (114           D. the biologic defect in the kidney is believed to involve the
mmol/L); bicarbonate 12 mEq/L (12 mmol/L); blood urea                 glomerular epithelial cell
nitrogen, 8 mg/dL (2.9 mmol/L); and creatinine, 0.3 mg/dL (26.5       E. the condition typically has an autosomal dominant inheritance
mcmol/L). A consulting nephrologist recommends measurement
of urine pH (which is 7.5) and urine ammonium (which is 12,000        Question 94 A 6-year-old boy presents with cola-colored urine.
mcM/L) (normal,>60,000 mcM/L). Of the following, the MOST             His mother reports that he had a sore throat 10 days ago. On
likely cause of this child's acidosis is                              physical examination, his blood pressure is 136/88 mm Hg, and
A. inborn error of metabolism                                         he has mild swelling of the face and lower extremities. Of the
B. lactic acidosis                                                    following, the MOST likely laboratory finding is
C. type I (distal renal tubular) acidosis                             A. low C3 complement value
D. type II (proximal renal tubular) acidosis                          B. normal urinalysis results
E. type IV renal tubular acidosis                                     C. positive antineutrophil cytoplasmic antibody titer
                                                                      D. positive antinuclear antibody titer
Question 62 A 4-month-old girl presents with fever. Results of        E. positive urine culture
urinalysis include 50 to 100 white blood cells per high-power field
and 3+ bacteria. Urine culture is positive for Escherichia coli.      Question 110 An 8-year-old boy presents with tingling in his
Ultrasonography reveals hydroureteral nephrosis of the left upper     lower extremities. He had been treated surgically for osteogenic
pole, and voiding cystourethrography shows a filling defect within    sarcoma and remains on a chemotherapeutic regimen that
the bladder (Item Q62A). Of the following, in addition to a urinary   includes cisplatin. He reports intermittent vomiting and loose
tract infection, the infant is MOST likely to have                    stools during his chemotherapy treatment. Physical examination
                                                                      shows no other findings of note. Among the results of laboratory
                                                                      evaluation are a magnesium value of 0.9 mg/dL (0.37 mmol/L)
                                                                      and a potassium value of 2.7 mEq/L (2.7 mmol/L). Of the
                                                                      following, the MOST likely explanation for this boy's electrolyte
                                                                      imbalance is
                                                                      A. cellular shifting due to changes in pH
                                                                      B. dietary deficiency
                                                                      C. losses due to recurrent diarrhea
                                                                      D. ongoing losses due to vomiting
                                                                      E. urinary losses due to tubular damage

                                                                      Question 126 An 18-month-old female presents with failure to
                                                                      thrive, polydipsia, and photophobia. Her weight is 8 kg and height
                                                                      is 70 cm (both <5th percentile). On physical examination, she
                                                                      appears pale and small for stated age, and she closes her eyes
A. bladder diverticulum                                               when you attempt to perform ophthalmoscopy. She has tacky
B. posterior urethral valves                                          mucous membranes and capillary refill of 2 to 3 seconds.
C. ureteral stone                                                     Pertinent findings on laboratory evaluation include: Sodium, 135
D. ureteropelvic junction obstruction                                 mEq/L (135 mmol/L) Potassium, 2.3 mEq/L (2.3 mmol/L)
E. ureterocele                                                        Chloride, 109 mEq/L (109 mmol/L) Bicarbonate, 14 mEq/L (14
                                                                      mmol/L) Blood urea nitrogen, 15 mg/dL (5.4 mmol/L) Creatinine,
Question 64 A 1-year-old year boy who has chronic kidney              0.3 mg/dL (26.5 mcmol/L) Calcium, 8.4 mg/dL (2.1 mmol/L)
disease from posterior urethral valves presents to your office        Phosphorus, 2.1 mg/dL (0.68 mmol/L) Magnesium, 1.4 mg/dL
because his breathing has been noisy for the past 2 hours. His        (0.56 mmol/L) Hemoglobin, 10.5 g/dL (105 g/L) Glucose, 102
usual medications include calcium carbonate and vitamin D. On         mg/dL (5.7 mmol/L) Of the following, the BEST test to establish
physical examination, you note inspiratory stridor. He has not had    the diagnosis is
upper respiratory tract symptoms or fever, and there is no history    A. a sweat chloride test
B. intact parathyroid hormone measurement                               are normal. Her growth parameters and physical examination
C. ophthalmologic examination                                           findings are normal. You prescribe oral trimethoprim-
D. urine ammonia measurement                                            sulfamethoxazole. Of the following, the MOST appropriate
E. urine chloride measurement                                           additional step to help reduce the incidence of further urinary
                                                                        tract infection is to
Question 150 You are evaluating a 17-year-old boy whom you              A. begin an evaluation for immunodeficiency
have known since early childhood. He is complaining of headaches        B. perform renal scintigraphy
over the past 2 weeks. He has a history of asthma, which has            C. prescribe a stool softener and regular bowel routine
been well controlled, and he is an otherwise healthy member of          D. prescribe oral oxybutynin
the varsity football team at school. He has had a significant           E. refer her to a pediatric nephrologist
weight gain of 30 lb (13.5 kg) since his visit to you 1 year ago. He
denies using illicit or prescription drugs. On physical examination,    Question 211 You are evaluating a 12-year-old boy as part of his
he appears very muscular and has a blood pressure of 180/120            annual health supervision visit. He has been in good health. His
mm Hg. You repeat the measurement using a leg cuff to ensure            heart rate is 75 beats/min and blood pressure is 132/82 mm Hg
adequate cuff size and obtain the same result. Of the following,        using the appropriate-sized cuff. His weight is above the 95th
the BEST management plan is                                             percentile, and his height is at the 50th percentile. He has strong
A. angiotensin-converting enzyme inhibition as an outpatient            pulses at the right brachial and right femoral regions. Of the
B. beta blocker therapy as an outpatient                                following, the MOST appropriate diagnostic evaluation to pursue
C. diuretic therapy as an inpatient                                     at this time is
D. repeat blood pressure measurement in 1 to 2 weeks                    A. blood urea nitrogen, creatinine, and electrolytes
E. vasodilator therapy as an inpatient                                  B. echocardiography
                                                                        C. radionuclide imaging of the kidneys
Question 158 You are evaluating a 10-year-old girl for a health         D. renal artery Doppler studies
supervision visit. Her weight and height are at the 50th percentile     E. urinary drug screen
for age, her blood pressure is 108/64 mm Hg, and there are no
unusual findings on physical examination. A screening urinalysis        Question 218 A mother brings in her 3-year-old daughter
shows a specific gravity of 1.030, pH of 6.5, 2+ blood, and no          because of daytime urinary incontinence and abdominal pain. The
protein. Urine microscopy reveals 5 to 10 red blood cells/high-         mother explained that the girl was toilet trained at 2 years of age.
power field.Of the following, the MOST appropriate next step is         On physical examination, growth parameters and vital signs are
A. abdominal computed tomography scan                                   normal, although the girl has mild suprapubic tenderness without
B. antinuclear antibody and complement measurement                      associated costovertebral angle tenderness or sacral dimples.
C. blood urea nitrogen and creatinine measurement                       Urinalysis shows a urine specific gravity of 1.025, pH of 6.5, 2+
D. referral for cystoscopy                                              blood, 1+ protein, 3+ leukocyte esterase, and positive nitrite.
E. repeat urinalysis in 2 weeks                                         Urine microscopy demonstrates 5 to 10 red blood cells/high-power
                                                                        field, 20 to 50 white blood cells/high-power field, and 3+ bacteria.
Question 173 One of your patients is a 6-month-old boy who              Of the following, the MOST likely etiologic agent is
had unilateral hydronephrosis detected prenatally.                      A. Enterococcus faecalis
Ultrasonography shows moderate hydronephrosis on the right and          B. Escherichia coli
a normal left kidney, and voiding cystourethrography shows no           C. Klebsiella pneumoniae
reflux, with a normal bladder and urethra. During a MAG                 D. Proteus mirabilis
3/furosemide renal scan, shortly after the furosemide is                E. Staphylococcus saprophyticus
administered, the infant becomes extremely fussy and difficult to
console.Of the following, the MOST likely diagnosis is                  Question 233 A 4-year-old female presents with fever, chills,
A. duplex collecting system with a ureterocele                          and vomiting. She has had abdominal pain and dysuria for 3 days.
B. multicystic dysplastic kidney                                        Her temperature is 104.2°F (40.1°C), and she has left-sided
C. nephrolithiasis                                                      costovertebral angle tenderness. Laboratory evaluation reveals a
D. obstructive uropathy from posterior urethral valves                  white blood cell count of 18.7x103/mcL (18.7x109/L) with 85%
E. ureteropelvic junction obstruction                                   neutrophils, 5% bands, 7% lymphocytes, and 3% monocytes. On
                                                                        urinalysis, the urine specific gravity is 1.025 and pH is 6.5, and
Question 188 During the routine examination of a 1-day-old              there is 2+ blood, 1+ protein, 3+ leukocyte esterase, and positive
term infant, you palpate an abdominal mass. His growth                  nitrite. Urine microscopy demonstrates 5 to 10 red blood
parameters and blood pressure are within normal limits. Of the          cells/high-power field, 50 to 100 white blood cells/high-power
following, the MOST likely explanation for the mass is                  field, and 3+ bacteria. Findings on renal/bladder ultrasonography
A. bowel duplication                                                    are normal. After a 3-day hospitalization for administration of
B. multicystic dysplastic kidney                                        intravenous antibiotics, discharge with a prescription for oral
C. neuroblastoma                                                        antibiotics is planned. Of the following, the MOST appropriate
D. renal vein thrombosis                                                study to complete this child's evaluation is
E. Wilms tumor                                                          A. abdominal computed tomography scan
                                                                        B. cystoscopy
Question 203 Voiding cystourethrography in a 9-month-old boy            C. intravenous pyelography
who has new-onset febrile urinary tract infection reveals grade II      D. MAG-3 renal scan with furosemide
vesicoureteral reflux (VUR). The parents ask you about their son's      E. voiding cystourethrography
prognosis. Of the following, you are MOST likely to explain that
A. approximately 80% of children who have newly diagnosed               Question 241 You are evaluating a 15-year-old girl in your office
febrile urinary tract infections have VUR when tested                   for her annual health supervision visit. She is doing well in school
B. once VUR is established, no follow-up radiologic testing is          and has no complaints about her health, although she would like
                                                                        to lose weight. She has joined the cross-country running team at
C. males have a worse prognosis than females
                                                                        school. She is not receiving any prescription medications but
D. referral to urology for ureteral reimplantation is warranted
                                                                        occasionally uses over-the-counter (OTC) cold remedies and
E. unilateral grade II reflux has a high likelihood of resolution
                                                                        vitamins. On physical examination, she appears thin but is in no
within 5 years of the diagnosis
                                                                        distress. Both her height and weight are at the 25th percentile for
                                                                        her age, although her weight has decreased from the 50th
Question 209 You are evaluating a 5-year-old girl who has a             percentile 1 year ago. Her heart rate is 100 beats/min and blood
urinary tract infection. She has had four lower urinary tract           pressure is 145/95 mm Hg. Other findings on physical
infections in the last 2 years, all of which resolved completely with   examination are normal. Of the following, the MOST appropriate
oral antibiotics. She denies symptoms of urgency and frequency.         next step is to
The only significant finding on her medical history is constipation.    A. evaluate for pheochromcytoma with blood and urine testing
Results of renal ultrasonography and voiding cystourethrography         B. order computed tomography scan of the abdomen
C. refer the girl for evaluation of anorexia nervosa
D. review the list of OTC medications she has used
E. screen for use of anabolic steroids

Question 248
A mother brings in her 4-year-old son because his eyelids are
swollen. On physical examination, the boy has normal growth
parameters, normal blood pressure, bilateral periorbital edema
(Item Q248A), and pitting pretibial edema. Laboratory findings
include normal electrolyte concentrations, blood urea nitrogen of
14 mg/dL (5 mmol/L), creatinine of 0.3 mg/dL (26.5 mcmol/L),
albumin of 1.9 g/dL (19 g/L), and normal C3 and C4 complement
values. Urinalysis reveals a specific gravity of 1.030, pH of 6.5,
4+ protein, and 1+ blood, and microscopy demonstrates 5 to 10
red blood cells/high-power field. Antinuclear antibody test results
are negative, and serologic tests are negative for hepatitis B                A. Diphenhydramine
surface antigen, negative for hepatitis C, and nonreactive for                B. Furosemide
human immunodeficiency virus. A purified protein derivative test              C. low-sodium diet
is nonreactive after 48 hours. Of the following, the MOST                     D. Prednisone
appropriate treatment for this patient is:                                    E. protein-rich diet

Renal PREP Answers 2007 and 2008

Question 45 Answer: C Primary enuresis is defined as the absence of achievement of dryness during the daytime, nighttime, or both. In
contrast to secondary enuresis, in which the child experiences a period of dryness after completing toilet training, primary enuresis generally
has an anatomic cause. The daytime wetting, history of recurrent urinary tract infections (UTIs), sacral dimple above the gluteal cleft, specific
gravity of 1.005 and no other abnormalities on urinalysis, and spinal dysraphism on magnetic resonance imaging reported for the girl in the
vignette are consistent with probable spina bifida occulta. The spina bifida may be associated with bladder dysfunction because innervation of
the bladder originates from the sacral spine, although some investigators believe that the association may be only an incidental finding.
Children who have bladder dysfunction of any cause exhibit dribbling, frequency, and recurrent UTIs due to bladder dyssynergy. This may
cause some degree of urinary tract obstruction because bladder emptying is interrupted. Such obstruction can be detected easily by
abdominal ultrasonography, which is far more accurate for documenting urinary tract anomalies than abdominal radiography. Abdominal
computed tomography scan may be more precise than ultrasonography for some conditions in the urinary tract, but it is far more expensive,
and the precision for detecting urinary tract obstruction is generally similar. A renal biopsy is indicated for children who have findings
suggestive of primary glomerular disease (eg, proteinuria), but would not be helpful to assess urinary tract anomalies. Finally, although
children who have bladder malformation may develop UTIs, the child in the vignette has no symptoms or findings on urinalysis suggestive of
a UTI. Moreover, a positive urine culture result will not aid in ascertaining the cause of her primary enuresis.

Question 77 Answer: C The kidneys have a full complement of glomeruli and tubules at birth, but the nephrons grow during childhood, with
most of the development occurring during the first 2 years. Thus, renal function may require up to 2 years to mature completely.
Development of glomerular function is generally complete by age 2 years. Tubular function matures rapidly during the first year after birth,
resulting in improved ability to reabsorb sodium, potassium, and water. In turn, the adaptability of the kidney to perturbations of normal body
homeostasis (eg, dehydration) is more pronounced after the first postnatal year than during infancy. The level of the mother's serum
creatinine generally determines the serum creatinine of the newborn in the first 7 to 10 postnatal days. The serum creatinine is relatively low
during infancy and early childhood due to lower muscle mass (Item C77A). Additionally, blood flow to the kidneys is lower in early infancy due
to increased peripheral resistance, thus reducing effective renal plasma flow. Taken together, these factors contribute to a lower serum
creatinine and a relatively lower glomerular filtration rate (GFR) during early childhood. GFR is determined routinely from the serum
creatinine, but there are several other methods to determine the GFR, including inulin clearance and measurement of serum cystatin A.

Question 93 Answer: A Detection of proteinuria on routine urine dipstick evaluation is an uncommon but perplexing dilemma for
pediatricians because proteinuria may suggest underlying renal disease or may represent a benign condition. It is incumbent on the
pediatrician to determine the appropriate steps to be undertaken in a child who has a urine dipstick positive for protein. Among the many
benign conditions causing a positive dipstick result for urinary protein are one of the following: a very concentrated urine (specific gravity
=1.020), alkaline urine (pH =7.5), or the presence of mucoproteins. In addition, acute illness may result in a small degree of proteinuria. The
most important feature of these conditions is that the urinary dipstick result almost never exceeds a reading of 1+. In the absence of these
conditions, it is vital to determine if the proteinuria is transient (orthostatic) or fixed. Orthostatic proteinuria (OP) occurs during the daytime
but disappears when the person is supine (eg, asleep) for at least 2 hours. Although the exact cause of OP remains controversial, it is a
benign condition that requires no follow-up or treatment. Children who have OP cannot have a history of renal disease, hematuria, or edema.
In contrast, fixed proteinuria is present at all times of the day, regardless of body position. The teenager in the vignette is asymptomatic and
has had several urinalyses (UAs) revealing 2+ protein but no other abnormalities. A negative first morning UA, with a urine protein-to-
creatinine ratio less than 0.2, would establish the diagnosis of OP. Prior to referral to the pediatric nephrologist, obtaining a repeat UA within
2 weeks and subsequently obtaining a first morning UA likely would have established the diagnosis of OP, obviating the need for several other
unnecessary tests (eg, electrolyte panel, complete blood count, serum complements). Renal ultrasonography may be helpful in detecting a
potential urinary tract malformation in some patients who may have proteinuria, but it is not the most appropriate first step. If the patient
has a positive (1+ or more) first morning UA result, renal biopsy may be indicated. A 24-hour urine collection (instead of a random protein-
to-creatinine ratio) rarely is necessary and does not aid in the diagnosis of OP. Proteinuria has been established firmly for this child, and
waiting for results from another daytime UA would only delay the diagnosis.

Question 109: Answer: B Gross hematuria is defined as discolored urine. The precise color may aid in establishing an origin of the "blood."
It is important to recognize that not all patients suspected of having gross hematuria have red blood cells (RBCs) in the urine. Indeed, the
urinalysis in some patients who have presumed gross hematuria may lack RBCs, suggesting the presence of myoglobin, hemoglobin, or
porphyrins, all of which may discolor the urine. Additionally, some foods (eg, beets), drugs, or additives (red dye) may discolor the urine. A
history should be obtained to ascertain a history of renal disease or urinary tract malformation; the duration of gross hematuria; associated
symptoms such abdominal, flank, or suprapubic pain (suggesting an infection or renal malformation); fever (suggesting an infection or renal
malformation); fever (suggesting an infection); or the passage of sand, gravel, or stones. The next step in determining the cause of gross
hematuria is to obtain a urinalysis to assess for blood, protein, and RBCs. The association of blood and protein in the urine with an elevated
blood pressure reported for the boy in the vignette strongly indicates new-onset glomerular disease. The low serum complement values are
consistent with acute glomerulonephritis (AGN). Of the options listed, only membranoproliferative GN (MPGN) and postinfectious AGN
(PIAGN) result in reduced serum complements, and of these two conditions, the C3 and C4 are reduced only in patients who have MPGN.
Although PIAGN is much more common than MPGN, only C3 is low in PIAGN. Patients who have immunoglobulin A nephropathy typically
develop recurrent episodes of gross hematuria, but the serum complement values are normal. Patients who have infections may develop
gross hematuria, but this is rare and usually is limited to viral cystitis. Finally, gross hematuria is common in patients who have
nephrolithiasis, but they usually experience pain and do not develop significant proteinuria or hypocomplementemia. One of the most
common causes of gross hematuria in children is hypercalciuria, with or without renal stones. Hypercalciuria usually is idiopathic, but it may
be due to causes of hypercalcemia (eg, hyperparathyroidism, malignancy, Addison disease, sarcoidosis, vitamin D therapy) or result from
increased urinary excretion of calcium (eg, furosemide therapy, Bartter syndrome, Dent disease [inherited hypercalciuria], distal renal tubular
acidosis). Gross hematuria may occur in patients who have sickle cell disease or trait due to intrarenal sickling and sludging.

Question 112 Answer: B Tetanus toxoid should be administered to all victims of massive trauma who have contaminated wounds and have
not received this vaccine within the past 5 years or whose immunization status is not known. For the patient described in the vignette, the
widespread areas of abrasion put him at particular risk for tetanus, much like a burn victim. A patient who has blood at the urethral meatus,
as described in the vignette, should be assumed to have a urethral injury. Blind placement of a Foley catheter is discouraged because such
action may convert a partial urethral tear into a complete transection. Retrograde urethrography should be performed to evaluate for this
injury. Upright abdominal films have no role in the evaluation of a patient who has had massive trauma. The cervical, thoracic, and
lumbosacral spine must remain immobilized during the initial management of such patients. Optimal radiologic evaluation of the abdomen in
major trauma victims is accomplished by computed tomography. Ideally, this should be performed using both intravenous and oral contrast.
Computed tomography of the head, not magnetic resonance imaging, is an important part of this patient's evaluation. Contrast adds no
information to the scan, so it should not be administered. Prophylactic antibiotics are not warranted for the patient in the vignette. Even in
the case of severe burns, prophylactic antibiotics do not significantly decrease the risk of secondary infections, and they may select for
resistant organisms.

Question 117 Answer: D Bedwetting (nocturnal enuresis) is primary if the child has never been dry at night. It is secondary when a child
has previously sustained dryness at night and subsequently resumes bedwetting. Only 2% to 3% of children who have nocturnal enuresis
have a contributing physical problem; most have either diminished bladder capacity (also evidenced by daytime wetting or dribbling) or
diminished nocturnal arousal (also evidenced by failure to awaken with wet clothes). This is a maturational problem, and parents should be
reassured that the problem generally resolves over time. Essentially, a child who has enuresis is unable to awaken to the sensation of a full
bladder or unable to awaken to urinate in the toilet. Secondary enuresis usually represents a "relapse" of physiologic primary enuresis. True
regression due to psychological stressors often results in diurnal enuresis or other behavioral regressions. No specific evaluation with
laboratory tests or imaging is required for either primary or secondary enuresis other than a clean voided specimen for urinalysis to exclude
diabetes and infection. Enuresis may be treated with expectant management. Other treatment modalities include alarms and medications.
Alarms may have a better long-term success rate than medications such as desmopressin, imipramine, or oxybutynin. These medications
have good short-term success rates but also are associated with more adverse effects.

Question 125 Answer: C Because routine screening of urine has become a common practice, many children who are otherwise
asymptomatic are being discovered to have microscopic hematuria. For most of these children who have no other urinary findings and are
asymptomatic, it is unlikely that an underlying cause will be ascertained. In contrast, determining a specific cause of gross hematuria in
children is far more likely. History and physical examination are essential for assessing the child who has gross hematuria. Pertinent
information includes the presence of prior renal disease and symptoms such as fever, pain, or edema. The physical examination should focus
on probing for edema, bruising, joint swelling, or rashes. Regardless of the findings, a urinalysis is mandatory. Blood and significant (greater
than 1+) protein are strongly suggestive of glomerular or interstitial disease. Microscopic analysis of a centrifuged urine specimen is
necessary to determine if red blood cells (RBCs) are present. In the absence of RBCs, other causes of a dipstick positive for "blood" include
hemoglobin, myoglobin, or porphyrins. The likelihood of myoglobinuria is strong for the boy described in the vignette because of the absence
of RBCs in the urine and the antecedent strenuous exercise. He probably has developed acute renal failure due to rhabdomyolysis, myoglobin
deposition in the kidney, and urinary tract obstruction. Hemoglobinuria is rare in the absence of hemolysis. Immunoglobulin A nephropathy
may present with gross hematuria, but RBCs should be detected on microscopic analysis. Although patients who have urinary tract infections
often have microscopic hematuria, gross hematuria is unusual. Finally, patients who have urolithiasis may develop gross hematuria, but
concomitant colicky pain is usually present. Myoglobinuria is caused by any process that involves excessive destruction of muscle or
rhabdomyolysis. This may occur after excessive, strenuous exercise in hot weather. Other causes of myoglobinuria include crush injury to
muscles from trauma, mitochondrial disorders, other inherited muscle diseases (eg, carnitine palmitoyltransferase II deficiency, McArdle
disease), malignant hyperthermia, or rarely after systemic viral illness or due to medication usage (eg, HMG-CoA reductase inhibitors).

Question 141 Answer: B Urinary tract obstruction (UTO) may indicate an abnormality in the kidney(s), ureter(s), bladder, or urethra. A
logical and stepwise approach to determine the cause usually results in reaching an accurate diagnosis. UTO generally is found in utero or
early in infancy. The advent of routine fetal ultrasonography has dramatically increased the detection of UTO prior to birth. In most other
cases of UTO, a urinary tract infection in infancy stimulates evaluation of the system. The practitioner's goal is to ascertain the site of
obstruction. Renal ultrasonography is the primary imaging technique used to determine if UTO is present, and if so, the degree of obstruction.
In general, hydronephrosis is described as mild, moderate, or severe. Most studies show that renal function is better preserved in mild
compared with moderate-to-severe hydronephrosis. Another invaluable piece of information is whether the hydronephrosis is unilateral or
bilateral. Obviously, bilateral hydronephrosis increases the likelihood of developing renal insufficiency, but it also may provide an indication of
the origin of obstruction. Generally, the origin of obstruction is lower with bilateral versus unilateral hydronephrosis. It is essential to
determine the cause of any obstruction; if left untreated, it may result in recurrent urinary tract infections and renal scarring and damage.
The bilateral hydronephrosis reported for the boy in the vignette strongly suggests the presence of UTO, although the hydronephrosis may be
nonobstructive. Voiding cystourethrography is necessary to determine if there is vesicoureteral reflux (VUR) (Item C141A), a ureteral
abnormality such as a duplicated ureter, or posterior urethral valves (PUV) (Item C141B). PUV must be considered a likely cause of bilateral
hydronephrosis in a male. The most common presentation of autosomal recessive or dominant polycystic kidney disease (Item C141C)is
enlarged kidneys in the newborn period, with or without small cysts; these kidneys do not display hydronephrosis. Although ureteropelvic
junction obstruction (UPJO) and VUR commonly cause hydronephrosis, the sex of the child and bilateral hydronephrosis makes PUV more
common. However, it should be emphasized that children who have PUV may have concomitant VUR or UPJO. Wilms tumor (Item C141D), the
most common abdominal tumor in infants, presents most commonly as a solid mass, occasionally with concomitant hydronephrosis.

Question 147 Answer: E The fractional excretion of sodium (FENa) is a measure of renal handling of solute. The equation for calculating the
FENa is: FENa = [(Urine Na x Plasma Cr)/(Plasma Na x Urine Cr)] x 100 Example: [(90 x 0.9)/(145 x 120)] x 100 = 0.5 Sodium is reabsorbed
in the proximal renal tubule. In the preterm kidney, a number of factors affect the renal handling of sodium. First, the renal blood flow
increases throughout gestation in the fetus and in the first week of postnatal life. Second, the glomerular filtration rate increases throughout
the first postnatal week. Third, the extracellular fluid compartment, where most of the total body content of sodium is located, is greatest in
the most preterm infants. Depending on the degree of prematurity, the functional number of nephrons may be reduced significantly
(nephrogenesis is not complete until after 36 weeks' gestation), and renal efficiency in handling solute load is reduced accordingly because
sodium transporter activity in the renal tubules is immature. Additionally, the premature kidney has poor concentrating ability, with maximal
urinary concentration of 600 to 800 mOsm/L in the first 2 weeks of postnatal life. This results in a high risk of hypervolemia and
hyponatremia (due to dilution) for the preterm infant who is given too much water. However, because of postnatal adjustments in fluid
compartments (Item C147A), the addition of sodium to intravenous fluids for the preterm neonate is largely unnecessary in the first 24 to 72
hours after birth. The very low-birthweight (VLBW) newborn described in the vignette has polyuria, generally defined as a urine output of
greater than 6 mL/kg per hour. Causes typically include iatrogenic overhydration, diabetes insipidus (genetic or sometimes related to
intracranial pathology), hyperglycemia with a corresponding osmotic drag of water and the occurrence of glycosuria, or anatomic renal
problems such as an obstruction that has been relieved. Water losses in the VLBW newborn generally exceed solute (sodium) losses,
especially in cases of polyuria, and dehydration with elevated serum sodium concentrations may result. As noted previously, sodium excretion
(FENa) decreases with increasing gestational age and postnatal age. Accordingly, the FENa is higher in a preterm newborn than in a term
infant. Phototherapy increases fluid (water) requirements for the VLBW newborn, but not sodium requirements. Intravenous sodium
supplementation is not necessary in most VLBW newborns in the first 24 to 72 hours of postnatal life.

Question 157 Answer: A Prune belly (Eagle-Barrett) syndrome (PBS) is a relatively uncommon condition resulting from poorly developed
abdominal musculature. Affected children may have a variety of urinary tract anomalies, including undescended testes, hydronephrosis,
posterior urethral valves (PUV), and bladder dysfunction. The lax abdominal musculature (Item C157A) and bilateral undescended testes
described for the boy in the vignette suggest the diagnosis of PBS. Abdominal ultrasonography and voiding cystourethrography are indicated
in all children who have PBS to study the entire urinary tract. Hydronephrosis is a common anomaly associated with PBS. The hydronephrosis
usually is obstructive and due to PUV or vesicoureteral reflux and ureteropelvic junction obstruction. Renal cysts are very uncommon, and
ureteroceles are seen only occasionally in children who have PBS. Some affected children may have nonobstructive hydronephrosis. The best
test to differentiate obstructive from nonobstructive hydronephrosis is renal scintigraphy. In obstructive hydronephrosis, the tracer cannot
escape the kidney, but in most kidneys with nonobstructive hydronephrosis, some amount of the tracer exits the kidney. The renal outcome
for children who have PBS is generally poor. Meticulous attention must be paid to the prevention of urinary tract infections (UTIs). Thus, it is
imperative to institute antibiotic prophylaxis if obstruction is present, and in some cases of moderate-to-severe hydronephrosis with
obstruction, early surgical repair is recommended. Urinary diversion via a vesicostomy or Mitrofanoff procedure (using the appendix to
connect the bladder to the abdomen, with exit near the umbilicus) may be indicated to prevent urinary stasis and UTIs. Unfortunately, renal
growth usually is compromised because of multiple abnormalities within the urinary tract, and most children who have PBS develop renal

Question 163 Answer: C The infant described in the vignette has a prenatal diagnosis of hydronephrosis and palpably enlarged kidneys on
physical examination. Despite a history of shunting in utero, there are no apparent shunts present on examination. Because this is not
uncommon when upper urinary tract obstruction is the problem, present techniques generally address direct drainage of renal calyces or cysts
by needle under ultrasonographic guidance. Hydronephrosis in the fetus, which may be physiologic and transient, or pathologic, is observed in
1 in 500 to 700 fetuses. Pathologic obstructive uropathy most frequently results from ureteropelvic junction obstruction or, less commonly,
ureterovesical obstruction. In males, the most common lower tract cause of obstructive uropathy is posterior urethral valves (Item C163A).
Obstruction of the emptying of the renal collecting system, ureters, or bladder may result in retrograde hydrostatic pressure and destruction
of the renal parenchyma. Rupture of the fetal urinary collecting system under these conditions is believed to cause urinary ascites. When an
obstruction is identified in a fetus, a vesicoamniotic shunt to relieve pressure and preserve renal function may be considered. The optimal
timing of delivery may be determined in balancing the effects of oligohydramnios and pulmonary hyperplasia against progressive renal
parenchymal loss. Unfortunately, efforts to mitigate the obstruction and consequential renal impairment by placing shunts have not met with
great success. Fetal shunts may become dislodged or obstructed, the accumulation of urine continues, and their placement imposes risks of
preterm labor and chorioamnionitis. Amniotic fluid volumes may be diminished in the presence of fetal urinary tract obstruction, which may,
in turn, lead to impaired fetal lung development, especially if the amniotic fluid volume is reduced during the canalicular stage of lung
development (16 to 24 weeks' gestation). Postnatal death from pulmonary hypoplasia is well described in affected patients. Although certain
fetuses who have lower urologic obstructions may benefit from vesicoamniotic shunting, patient selection is difficult, and no large randomized
trials have demonstrated clear benefit. At present, placement is reserved for fetuses whose delivery is not imminent and who have a high risk
for pulmonary hypoplasia due to the presence of oligohydramnios. Postnatally, infants who have obstructive uropathy are at increased risk for
urinary tract infection, vesicoureteral reflux, hydronephrosis, and possibly respiratory distress, but these conditions do not typically lead to
fetal or neonatal death. Respiratory distress may be related to impingement of renal masses on the diaphragm, urinary ascites, or an element
of pulmonary hypoplasia. Although simple, transient, physiologic hydronephrosis may resolve spontaneously, obstructive uropathy does not.

Question 173 Answer: E Urethral stricture disease involves blockage or narrowing of the urethra that causes reduced urine flow during
voiding. Most urethral strictures occur in males. The most common causes in children are previous trauma (eg, posterior urethral injury
occurring as a consequence of pelvic fracture) or instrumentation of the urethra, infection (eg, gonorrhea), congenital anomaly, idiopathic,
and as a complication of balanitis (balanitis xerotica obliterans). Children who have urethral strictures can develop a variety of signs and
symptoms, including straining to urinate, a decrease in the size and force of the urine stream, persistent sense of bladder fullness, urine
dribbling, and frequency and urgency of urination. Overt physical examination findings are generally absent. Diagnosis is confirmed by
cystoscopy. Alternatively, voiding cystourethrography can be performed to determine the extent of the stricture or ultrasonography may be
performed. Treatment of a urethral stricture depends on the length, location, and persistence of the stricture. In general, initial urethral
strictures that are short (<1.5 cm) can be treated with either endoscopic incision or dilation. Although this form of treatment has only a
modest success rate, it is minimally invasive and associated with few procedure-related complications. Recurrent strictures or strictures
longer than 2 cm usually are not amenable to endoscopic incision or dilation, and this form of therapy proves to be a "temporizing" measure
without much long-term success. Severe urethral stricture in males may damage the bladder and cause hydronephrosis. Carcinoma of the
urethra is rare in children, and the boy described in the vignette has no history of chronic infection. Moreover, chronic gonorrhea is
uncommon at this age. The boy's age effectively eliminates congenital narrowing as a cause; symptoms usually develop in early childhood.
Chronic intermittent urolithiasis is a very rare cause of urethral stricture, especially in patients who have no history of chronic abdominal or
flank pain.

Question 179 Answer: D The infant described in the vignette is growth-restricted, has a flank mass consistent with an enlarged kidney, and
has the characteristic phenotype of the fetal oligohydramnios sequence. Bilateral renal aplasia (true Potter syndrome), which occurs in 1 per
3,000 births, or severe dysplasia, such as that seen in multicystic dysplastic or hereditary polycystic kidney disease and resulting in
oligohydramnios (Potter sequence), both jeopardize fetal and neonatal well-being. Renal aplasia/dysplasia in the fetus results in
oligohydramnios that alters amniotic fluid dynamics and interrupts normal development of the fetal lung, especially during the canalicular
stage of lung development from 16 to 24 weeks' gestation. Pulmonary hypoplasia results and may prove fatal in the neonatal period despite
efforts at assisted ventilation. An additional complication of this aberrant renal development is reduced intrauterine volume, resulting in fetal
constraint. In such instances, the growth restriction is generalized, the facies is flattened (Item C179A), the ears appear low-set, the arms
and legs may be malpositioned with clubbing of the feet (Item C179B) and joint contractures, and breech presentation is not uncommon.
Alport disease is an inherited condition (X-linked in 85% and autosomal recessive in 15%) that involves the kidneys, cochlea, and eyes,
leading to sensorineural deafness and nephritis. The defect affects type IV collagen, and clinical stigmata do not present in the newborn
period. Congenital nephrotic syndrome is characterized by edema, ascites or hydrops, and associated proteinuria, hyperlipidemia, and
hypoalbuminemia. It is most common among families that have Finnish ancestry. Wilms tumor, also known as a mesoblastic nephroma, may
be congenital and may be associated with aniridia, hemihypertrophy, or Beckwith-Wiedemann syndrome. Findings on the physical
examination include hypertension, hematuria, and a flank mass. Turner syndrome is due to an absence of part or all of one of the X
chromosomes. Renal anomalies seen in this condition include renal aplasia or hypoplasia, rotated or horseshoe kidneys, or renal duplication.
The clinical phenotype includes growth restriction, lymphedema of the dorsal aspects of the hands and feet, cystic hygroma, and
cardiovascular defects such as coarctation of the aorta and other left-sided cardiac outflow tract lesions.

Question 189 Answer: C Alport syndrome (hereditary nephritis) is an uncommon disease, affecting about 1 in 5,000 persons. There are
several modes of inheritance, the most common being X-linked. Although there is a male-to-female ratio of 1:1, men are affected earlier and
more severely than women. Other modes of inheritance include autosomal dominant, autosomal recessive, and heterogeneous. Females who
have the defective gene on one of their two X chromosomes usually are asymptomatic, although they may exhibit some degree of minor renal
insufficiency; most females who have Alport syndrome have some blood in the urine. Males who have the defective gene usually develop
renal failure between the second and third decades of life. In most cases, the mutation lies in abnormal collagen type IV (COL4A) protein that
is an essential part of the glomerular basement membrane. Other conditions that may be inherited and present with hematuria, such as
benign familial hematuria and thin membrane disease, are associated with significantly more favorable renal outcomes than is seen with
Alport syndrome. The primary characteristics of Alport syndrome are progressive renal failure, sensorineural hearing deficits, and
abnormalities of the lens of the eye (lenticonus). Uncommon associated conditions include immunologic abnormality of skin, disorders of
platelets, abnormalities of white blood cells, and smooth muscle tumors. Alport syndrome can be diagnosed by several methods. Most
commonly, it is diagnosed initially by testing the urine (for blood) of persons who have an affected family member. The urine result may be
confirmed by performing a kidney biopsy and assessing for the presence or absence of the COL4A protein. In certain cases, testing for the
abnormal gene in Alport syndrome may be performed. The strong family history of renal disease with associated hearing deficits reported for
the boy in the vignette is very suggestive of Alport syndrome. Based on the usual mode of inheritance, it can be assumed that the boy will
develop end-stage renal disease, but his sister may develop only minor kidney disease or simply be a carrier of the gene. The family history
suggests that the boy likely also will develop some degree of hearing deficits. Unusual associated anomalies, including esophageal
leiomyomatosis and giant cell thrombocytopenia, are seen only occasionally in Alport syndrome and usually are associated with autosomal
modes of inheritance. The family history indicates that this boy has inherited the disease through an X-linked pattern.

Question 195 Answer: D The causes of acute renal failure (ARF) in the newborn include: dehydration, sepsis, congestive heart failure, toxic
effects of certain drugs (angiotensin-converting enzyme inhibitors, indomethacin, amphotericin), acute tubular necrosis, congenital renal
dysplasia, renal vein thrombosis, and obstructive uropathies (posterior urethral valves, neurogenic bladder, bilateral ureteropelvic junction or
ureterovesical junction obstruction). The infant described in the vignette, who has not passed urine 50 hours after birth and who has a
palpably full bladder, should be evaluated thoroughly. Anuria in a newborn for more than 24 hours warrants an evaluation that includes a
thorough history (including obstetric history and drug exposure), review of any prenatal ultrasonography images, assessment for evidence of
perinatal asphyxia or sepsis, and a family history of renal disease. The physical examination should address the genitalia, abdomen, and
flanks as well as any signs of edema or oligohydramnios sequence. Laboratory evaluation should attend to serum electrolytes, urea nitrogen
and creatinine, urinalysis, urine culture, and urinary electrolytes and creatinine. To obtain urine and complete the evaluation of the patient, a
urinary catheter must be placed. Doing so will answer two questions:Are the urethra and bladder outlet patent or obstructed? Have the
kidneys produced any urine? Once urine is obtained, the laboratory evaluation can be completed and a fractional excretion of sodium (FENa)
calculated to assist in distinguishing prerenal ARF (FENa ≤1.0) from intrinsic ARF (FENa >1.0). If no urine can be obtained by catheterization,
ultrasonography of the kidneys, ureters, and bladder should be performed. Neither nuclear renal scan nor intravenous pyelography should be
performed until urine flow is established. A urologist may be consulted, but bladder catheterization should be performed first.

Question 205 Answer: E The girl in the vignette has painless gross hematuria without fever. Fever would suggest possible infection, and
abdominal pain would hint at infection, stone, or renal malformation (tumor, cyst). She has an elevated blood pressure and periorbital edema,
which may be due to hypoalbuminemia or fluid retention. Her urinalysis shows blood and protein. The most significant clue to the cause of her
renal disease is her low serum complement 3 (C3) concentration and normal C4 concentration. She has strong evidence of nephritis (gross
hematuria, hypertension, periorbital edema), decreased C3, and normal C4 values, which are consistent with postinfectious acute
glomerulonephritis (PIAGN). If both the C3 and C4 values were low, the nephritis more likely would be membranoproliferative GN or lupus
nephritis. Children who have either focal segmental glomerulosclerosis or immunoglobulin A nephropathy may develop gross hematuria,
hypertension, edema, and nephritis, but because of the pathogenesis of these diseases, the serum complement values would be normal.
PIAGN is a common but generally self-limited renal disease that usually occurs in childhood. Among the several known pathogenetic
organisms associated with PIAGN, the most common is group A beta-hemolytic Streptococcus. Most children who have PIAGN recover
complete renal function and exhibit normalization of C3 levels by 6 weeks, although some continue to exhibit hematuria and/or proteinuria for
prolonged periods after initial presentation. Some also have hypertension, primarily due to salt and water retention, for up to 3 months.
Occasionally, the disease may assume a rapidly progressive course, resulting in acute renal failure and the need for treatment with high-dose
intravenous corticosteroids and possibly intravenous cyclophosphamide or dialysis if renal failure persists. In these patients, the renal
outcome is guarded.

Question 221 Answer: C Nephrotic syndrome (NS) is a constellation of symptoms that include proteinuria, hypoalbuminemia, edema, and
hyperlipidemia. The most important aspect is proteinuria; the other symptoms simply are outcomes of excessive urinary protein leak.
Proteinuria is not the only cause of hypoalbuminemia; other causes include advanced liver disease, severe malnutrition, and gastrointestinal
losses. If NS is suspected, a urinalysis may provide clues to the cause. Among the many causes of NS in children, the most common are
minimal-change NS (MCNS), focal segmental glomerulosclerosis (FSGS), membranous nephropathy (MN), any cause of acute
glomerulonephritis (AGN), membranoproliferative GN (MPGN), lupus GN, and immunoglobulin A nephropathy (IgAN). The practitioner's goal is
to determine the cause of NS to devise the best management plan. Although most glomerular diseases are not inherited, a family history of
renal disease may suggest FSGS, LN, or IgAN. Urinalysis may be helpful, with the presence of blood making MCNS, FSGS, and MN less likely,
although any of these conditions may feature protein and blood in the urine. Measuring serum electrolytes is essential to determine overall
renal function in any child who has NS, but it is unlikely to provide any clues to the cause. An important clue may be obtained by assessing
serum levels of complement 3 and 4. Normal serum complement values, as reported for the boy in the vignette, generally eliminate
postinfectious AGN, MPGN, and Tupus nephritis due to Henoch-Schönlein purpura as the cause of NS. The older age of the boy described in
the vignette, absence of hematuria, and normal serum complement values suggest MN as the most likely cause of his renal disease. Another
common cause could be FSGS. MCNS is most common in toddlers and early school-age children; MN, MPGN, and IgAN generally present in
older (>10 years of age) children.
Question 222 Answer: A Multiple antibiotic classes can cause renal toxicity, but the class that is the most likely to cause nephrotoxicity is
the aminoglycosides (gentamicin, tobramycin, amikacin, streptomycin, and kanamycin). The renal toxicity of these agents is related to their
concentrative uptake by the proximal renal tubular cells and their capacity to interact with critical intracellular targets. Risk factors associated
with the development of such nephrotoxicity include prolonged course of therapy, supertherapeutic doses, concurrent use of other
nephrotoxic medications, dehydration, and underlying liver disease. The development of nephrotoxicity is characterized by the gradual onset
of partial-to-complete, reversible, nonoliguric renal failure. The patient may exhibit hypertension, and laboratory evaluation demonstrates
elevations in blood urea nitrogen and creatinine values as well as elevated protein concentrations on urinalysis. Nephrotoxicity rarely is
associated with the other antibiotics listed.

Question 237 Answer: B Immunoglobulin A nephropathy (IgAN) or Berger disease is the most common cause of primary glomerulonephritis
in adults in the world. In contrast, only about 5% to 10% of children who have glomerular disease exhibit IgAN. Although once considered to
be a random disease with no genetic component, the prevailing opinion now is that there may be a strong familial component to IgAN. The
pathogenesis of IgAN remains elusive. It is not a classically defined autoimmune disease, although the disease develops from deposition of
IgA-containing immune complexes in the kidney. It is tempting to assume that the pathogenesis is related to mucosal IgA because the
disease often follows an upper respiratory tract infection, but deposited IgA is predominantly polymeric IgA1. The association of some cases
of IgAN with syndromes that affect the respiratory or gastrointestinal (GI) tracts supports the relationship between IgAN and the immune
system. Moreover, it has been shown that the gross hematuria worsens during or after upper respiratory tract or GI infections. Serum IgA
concentrations may be elevated in about 50% of patients who have IgAN, making this finding relatively nonspecific and not diagnostic. The
natural history of the disease varies. About one third of patients have a benign course, one third experience slow progression to renal failure,
and one third have a more progressive course in which renal failure develops within 20 years. IgAN is more common in whites and Asians
than other ethnic groups and is observed frequently in American Indians. IgAN is more common in males than females. The girl in the
vignette has the classic presentation of IgAN: a brief history of painless, gross hematuria following an upper respiratory tract infection. Her
urinalysis demonstrates too numerous-to-count red blood cells but no protein, and her renal function is normal. Children who have focal
segmental glomerulosclerosis may develop gross hematuria, but this is not common. Patients who have lupus nephritis may develop either
microscopic or gross hematuria, but they often have associated symptoms (eg, rashes, arthritis, anorexia). Children who have
membranoproliferative glomerulonephritis may develop gross hematuria, but they often present with proteinuria, edema, and hypertension.
Finally, children who have papillary necrosis usually have sickle cell disease or trait, and the gross hematuria generally is associated with
pain, typically abdominal or flank pain. The follow-up of a patient who has IgAN includes at least quarterly assessment of urine protein by
urinalysis and determination of a random protein-to-creatinine ratio (P/C). A rising urine P/C is highly predictive of progressive renal disease.
Frequent measurement of serum electrolyte values is vital, especially for patients who have evidence of significant proteinuria or
hypertension. Treatment typically begins with agents to reduce proteinuria: angiotensin-converting enzyme inhibitors or angiotensin receptor
blockers. Oral corticosteroids may be effective in some cases but generally do not alter the final outcome significantly. Use of calcineurin
inhibitors such as cyclosporine or mycophenolate mofetil has been shown to slow the progression of IgAN in adults, but larger trials are
necessary to determine their efficacy fully.

Question 253 Answer: C The infant described in the vignette presents with failure to thrive, and measurement of his serum electrolytes
reveals a normal anion gap and hyperchloremic metabolic acidosis. The key element in his presentation is the urine pH, which is 7.5,
indicating that it is highly alkaline. In proximal renal tubular acidosis (RTA), as the urine leaves the proximal tubule, the relative inability to
reabsorb bicarbonate results in a very alkaline pH of the tubular fluid. However, the distal tubule in patients who have proximal RTA is
healthy, and it extrudes high quantities of acid, dropping the tubular pH to a lower value (=6.0). In contrast, because the distal nephron
represents the last real opportunity for the kidney to regulate acid-base balance, children who have distal RTA cannot adequately compensate
for the lack of acid extrusion, resulting in very alkaline urine. The urine ammonium value in the child in the vignette is very low at 12,000
mcM/L (normal >60,000 mcM/L), which is consistent with reduced acid (as part of ammonium) secretion and strongly predictive of distal RTA.
RTA is a common cause of metabolic acidosis in childhood. There are two primary types of RTA: proximal or type II and distal or type I. Type
IV RTA, also called hyperkalemic RTA, is uncommon and will be discussed only briefly. A review of basic renal physiology in the maintenance
of acid-base balance is necessary to understand RTA. The primary responsibility of the proximal tubule in the preservation of normal acid-
base homeostasis is to reabsorb filtered bicarbonate. It achieves this goal by reabsorbing water and carbon dioxide from the renal (apical
membrane) tubule into the cell and then converting them to hydrogen and bicarbonate within the cell. Hydrogen is extruded back into the
tubule, and bicarbonate is reabsorbed at the other end (basolateral membrane) of the cell. Thus, the reabsorption of base (bicarbonate) is
linked with the expulsion of acid (hydrogen). In contrast, the primary role of the distal tubule is to secrete acid, either as free hydrogen ion,
as part of ammonium (ammonia plus hydrogen), or linked to phosphorous. The distal nephron does play a role in bicarbonate reabsorption,
but its primary role is to secrete acid. Because children who have proximal (type II) RTA have difficulty reabsorbing bicarbonate, the serum
bicarbonate concentration falls, resulting in acidosis. In distal (type I) RTA, the distal tubule struggles to secrete acid. This excess acid must
be buffered in the blood, principally by bicarbonate, which also results in a decline in the serum bicarbonate or acidosis. In distal RTA, there
may be concomitant proximal tubule disturbances. The level of the serum bicarbonate in either proximal or distal RTA may vary, depending
on the extent of the deficit. To maintain electroneutrality in RTA, the loss of bicarbonate is compensated by the retention of chloride, also a
negatively charged ion. Thus, the anion gap ([sodium]-[chloride + bicarbonate]) is maintained at 10 to 16. In other types of acidosis, such as
lactic acidosis, the excess accumulation of acid does not induce an increase in chloride absorption and, thus, the anion gap is elevated. Given
the normal anion gap, this child cannot have either an inborn error of metabolism or lactic acidosis, which typically results in a high (>16)
anion gap. Additionally, the normal serum potassium value effectively eliminates type IV RTA as a cause of the acidosis because the lack of
aldosterone or renal resistance to aldosterone in this condition induces acidosis and hyperkalemia.

Question 62 Answer: E A ureterocele is a cystic dilation of the ureter where it inserts into the bladder. An intravesical ureterocele is
contained entirely within the bladder. When a portion of the defect extends beyond the bladder (to the urethra or bladder neck), an
extravesical ureterocele is present. Typically, the pelvocaliceal system draining into the ureterocele is obstructed. The incidence of
ureteroceles in children is estimated between 1 in 5,000 and 1 in 10,000. Ureteroceles are associated with a duplex collecting system in 80%
of children; the remainder are associated with a single collecting system. Ureteroceles are four times more common in females than males
and occur almost exclusively in Caucasians.A ureterocele is associated most commonly with a complete duplication of the renal collecting
system (more common in the left kidney) where the involved ureter is linked to that draining the upper pole moiety. This lesion, which
extends beyond the ureterovesical junction, results in ureteral obstruction, with hydroureteral nephrosis of the involved renal unit, usually the
upper pole, as described for the infant in the vignette. A ureterocele often results in a mass lesion within the bladder that may be seen on
bladder ultrasonography or indirectly as a filling defect of the bladder on voiding cystourethrography (Item C62A). The lower pole of the
kidney of a duplex collecting system may drain into an orthotopic site and is associated with vesicoureteral reflux (VUR) in approximately
50% of cases. In addition, VUR is seen in approximately 25% of the kidneys contralateral to the duplex kidney that has a ureterocele.
Ureteroceles most commonly are associated with urinary tract infection in infants, although 25% are detected antenatally. Older children
present with voiding symptoms or hematuria associated with minimal trauma. Surgical treatment is aimed at relieving the obstruction,
preserving the functioning nephron mass, removing nonviable tissue that may result in infection, and treating VUR. Based on patient
symptoms, treatments include upper pole nephroureterectomy, endoscopic incision of the ureterocele for relief of obstruction, and clinical
observation. Ureteropelvic junction obstruction (Item C62B), ureteral stones (Item C62C), and posterior urethral valves (Item C62D) cause
hydronephrosis that involves the entire kidney, not just a portion, as is seen with a ureterocele. In addition, in posterior urethral valves, the
hydronephrosis is bilateral. A bladder diverticulum (Item C62E) results in an outpouching of the bladder wall without a filling defect in the

Question 64 Answer: C Serum calcium and 1,25 dihydroxyvitamin D concentrations are decreased in children who have chronic kidney
disease because of phosphate retention and impaired hydroxylation of 25-hydroxyvitamin D. Physiologic serum calcium concentrations are
maintained largely through the use of vitamin D supplements and phosphate binders. As renal function worsens, hypocalcemia can result if
vitamin D deficiency or hyperphosphatemia is not addressed or if the use of bicarbonate therapy to treat metabolic acidosis leads to metabolic
alkalemia. Metabolic alkalemia increases the binding of calcium to albumin, which decreases the ionized calcium concentration. Decreased
ionized calcium can lead to perioral or extremity paresthesias, carpopedal spasm, laryngospasm, and seizures. Children who have
hypocalcemia from any cause may be diagnosed mistakenly with croup if they present with tetany-related laryngospasm. Hyperkalemia may
lead to muscle weakness and paresthesias and abnormalities in cardiac conduction. Clinical manifestations usually are preceded by conduction
abnormalities, which may result in ventricular fibrillation and asystole. Hypermagnesemia generally is not associated with clinical symptoms.
Severe hypophosphatemia can cause proximal muscle weakness, cardiac dysfunction, ataxia, seizures, and coma. Hyponatremia is a cause of
nausea, vomiting, hypothermia, lethargy, agitation, headache, and seizures.

Question 78 Answer: A The adolescent male described in the vignette has hematuria and proteinuria documented on a health supervision
visit and a history of cola-colored urine temporally associated with an upper respiratory tract illness 6 weeks earlier. Such findings suggest
the presence of an underlying glomerulonephritis that can range from overt disease with gross hematuria when accompanied by an
intercurrent illness to a subclinical state with persistent abnormal urinary findings.The evaluation of a child who has glomerulonephritis should
begin with careful measurement of blood pressure and renal function (serum creatinine) to assess the severity of the clinical situation,
followed by a serologic evaluation to screen for an underlying cause. The normal complement components C3 and C4 described for this boy
suggest three likely diagnostic possibilities: immunoglobulin A glomerulonephritis, pauci-immune vasculitis, or familial nephritis. The
discovery of hematuria in the mother suggests familial nephritis.Familial nephritis can be caused by either Alport syndrome (AS) or thin
glomerular basement membrane (GBM) disease. Both disorders involve underlying defects of the GBM that result in a disruption of the
glomerular capillary barrier. This barrier is comprised of the glomerular endothelial cell, the GBM, and the podocyte (visceral glomerular
epithelial cell). Any disruption to this barrier permits access of restricted substances, such as red blood cells or protein, to the urinary space.
AS is not caused by immune complex deposition, small vessel vasculitis, or defects in the glomerular epithelial cell.AS is caused by a defect of
type IV collagen, a component of the GBM. The cause in 80% of cases is an X-linked disease involving a gene defect of COL4A5 (which codes
for the alpha 5 chain of type IV collagen). A common presentation for AS is a male child who has asymptomatic microscopic hematuria that
may become overt hematuria in the presence of a respiratory infection. The renal lesion may progress to azotemia with nephrotic-range
proteinuria in adolescence. End-stage renal disease has been reported in 50% to 90% of affected males by age 30 years, depending on the
severity of the genetic defect. High-frequency sensorineural hearing loss occurs in approximately 50% of affected patients. A number of
patients also have ophthalmologic findings, with anterior lenticonus, a defect of the lens bowing into the anterior chamber, being the most
common. Due to the X-linked inheritance of this disorder in most patients, males often present earlier than females and have more severe
disease. As such, males are more likely than females to develop chronic renal failure. As in this case, the evaluation of a male child who has
persistent asymptomatic hematuria should include a dipstick urinalysis of the mother to screen for hematuria. Based on the genetics of this
disorder, 50% of male children of female carriers are affected. At present, there is no specific treatment for AS. Nephrologists focus on blood
pressure control and reduction of proteinuria, often with the use of angiotensin-converting enzyme inhibitors.Genetic defects of the alpha 3 or
alpha 4 chain of type IV collagen result in an autosomal form of AS (autosomal recessive or dominant), which comprises the remaining 20%
of cases of AS.Thin GBM disease has overlapping characteristics with AS in that it runs in families, is caused by a defect of the GBM, and
results in persistent microscopic hematuria. Recently, thin GBM disease has been traced to a heterozygous state for the gene defect of alpha
3 or alpha 4 of type IV collagen, which explains why it has a much more favorable prognosis than AS.

Question 94 Answer: A The findings of cola-colored urine, swelling, and hypertension described for the boy in the vignette suggest the
diagnosis of acute glomerulonephritis. The "sore throat" 10 days earlier makes acute poststreptococcal glomerulonephritis (APSGN) the most
likely diagnosis. The initial assessment of a child in whom ASPGN is suspected must include measurement of blood pressure and serum
creatinine to assess disease severity. Both severe hypertension and renal failure can occur as part of a rapidly progressive glomerulonephritis.
After initial assessment, the most important diagnostic test is measurement of complement component 3 (C3) to confirm the presence of
hypocomplementemia, which occurs in more than 90% of cases. ASPGN is an immune complex-mediated glomerulonephritis that follows an
infection by a nephritogenic strain of group A beta-hemolytic Streptococcus of the pharynx or skin. The interval between pharyngitis and the
development of APSGN is approximately 1 to 2 weeks. In contrast, the latency period between a skin infection and ASPGN is 3 to 6 weeks.
Most patients who have nephritis have a subclinical infection, which is estimated to occur four to five times more frequently than overt
disease. APSGN in children is characterized by hematuria (100%), proteinuria (80%), edema (90%), hypertension (70%), and azotemia
(33%). Thus, the urinalysis will not be normal. In addition, gross hematuria occurs in approximately 40% of children who have overt disease.
As noted previously, the characteristic laboratory feature of ASPGN is hypocomplementemia, which typically features depressed C3 and
normal C4 values. The differential diagnosis of hypocomplementemic glomerulonephritis consists of membranoproliferative glomerulonephritis
(MPGN) in a child who has disease limited to the kidney and systemic lupus erythematosus in a child who has multisystem disease. Rarer
causes of hypocomplementemic glomerulonephritis include subacute bacterial endocarditis, shunt nephritis (in patients who have
ventriculoatrial shunts), and essential mixed cryoglobulinemia. Treatment of ASPGN is typically supportive and aims to reverse the sodium
and fluid retention through the use of diuretics accompanied by restriction of sodium and fluid. Vasodilators also may be used for patients
who have severe hypertension. Antibiotics can reduce the risk of transmission of the nephritogenic strain of streptococci to close contacts. The
key follow-up test is a repeat measurement of C3, which usually normalizes within 8 weeks. Patients in whom depression of C3 persists after
12 weeks may require a renal biopsy to rule out MPGN. The prognosis of ASPGN is excellent. Gross hematuria and hypertension usually
resolve within a few weeks and proteinuria within a few months. Microscopic hematuria may persist for 1 to 3 years. A normal urinalysis
result is inconsistent with any form of glomerulonephritis, and would, therefore, be highly unlikely in a child who has hypertension and cola-
colored urine. A positive urine culture would be unexpected in this clinical scenario. Patients who have hemorrhagic cystitis typically have
bright red blood in the urine, often accompanied by clots. Other pertinent parts to the history that are absent in this scenario would be
symptoms of dysuria, abdominal pain, frequency, urgency, and possibly fever. Small vessel vasculitides such as Wegener granulomatosis,
microscopic polyangiitis, and Churg Strauss disease are less common causes of glomerulonephritis and, therefore, anti-neutrophil cytoplasmic
antibody testing is unlikely to be revealing. Another, less likely diagnostic possibility for the child in the vignette is lupus nephritis. However,
anti-nuclear antibody should be measured in the setting of acute nephritis to exclude this possibility.

Question 110 Answer: E The symptoms of tingling described for the boy in the vignette may be associated with hypomagnesemia and
hypokalemia. Cisplatin is a chemotherapeutic agent that can cause acute losses of magnesium and potassium and chronic losses in some
patients that necessitate chronic oral replacement of these electrolytes. Chemotherapeutic agents used to treat pediatric malignancies are
associated with a number of untoward complications, including nephrotoxicity. The two classes of drugs that most commonly cause renal
toxicity are the platinum drugs (cisplatin and carboplatin) and ifosfamide. The platinum drugs (cisplatin more than carboplatin) cause injury to
the late proximal tubule and collecting duct. More specifically, the proximal tubular damage can result in alterations of the brush border and
tubular necrosis. The clinical manifestations of this damage are polyuria, electrolyte abnormalities, and azotemia. Inappropriate tubular losses
of magnesium, sodium, and potassium are typical and result in the need for aggressive replacement. Prevention of cisplatin-associated
nephrotoxicity has been aimed at optimizing hydration before, during, and after the infusion. Mannitol also may be used. Studies have shown
that although many of the effects of cisplatin are temporary, altered renal function and magnesium wasting persist in many patients in long-
term follow-up. Ifosfamide, which is used to treat many pediatric solid tumors, has been associated with acute and chronic nephrotoxicity.
This agent can result in the Fanconi syndrome due to damage to the early portion of the proximal tubule. As a result, glycosuria,
phosphaturia, amino aciduria, proteinuria, and altered glomerular filtration rate can be seen. The risks of ifosfamide nephrotoxicity appear to
be related to the age of the patient, coexisting nephrotoxins, and nephron mass (with worse outcomes in patients who have prior unilateral
nephrectomy). Serum potassium concentrations can be influenced by a number of factors, including dietary intake, intestinal absorption, and
urinary excretion. Because potassium is primarily intracellular, in the setting of alkalosis, it shifts intracellularly, and the serum concentrations
decrease. Like potassium, magnesium is primarily contained intracellularly. It is absorbed in the ileum, and its extracellular concentrations are
regulated in the kidney.When hypomagnesemia and hypokalemia occur together, renal causes should be strongly considered. A metabolic
alkalosis may cause the serum potassium to fall, but should have minimal effect on magnesium. Moreover, the patient described in the
vignette is not believed to be at risk for an alkalosis. In the setting of normal renal function without ongoing losses, magnesium and
potassium concentrations would be expected to be normal, even in the setting of a dietary deficient in these minerals. The patient has only
intermittent vomiting and loose stools, making losses from the gastrointestinal tract unlikely.

Question 126 Answer: C The child described in the vignette has failure to thrive; symptoms of polyuria and photophobia; signs of apparent
mild dehydration; and laboratory findings that include hypokalemia, metabolic acidosis, and hypophosphatemia. Such electrolyte disturbances
are characteristic of Fanconi syndrome, a proximal tubulopathy that results in urinary losses of sodium, potassium, bicarbonate, phosphate,
amino acids, protein, and glucose. Although the differential diagnosis for the causes of Fanconi syndrome in the pediatric patient is extensive,
the condition often is due to a metabolic disturbance. Causes of Fanconi syndrome include inherited diseases such as glycogen storage
disease, hereditary fructose intolerance, tyrosinemia, cytochrome c oxidase deficiency, galactosemia, Lowe syndrome, Wilson disease, Dent
disease, and cystinosis. Acquired causes include heavy metal poisoning, ifosfamide, cisplatin, gentamicin, and ingestion of outdated
tetracycline. The most common cause of Fanconi syndrome in pediatrics is nephropathic cystinosis. Cystinosis is a lysosomal storage disorder
that affects all cells in the body. Cystine normally is a product of protein degradation that is transported out of the lysosome. In cystinosis,
cystine accumulates within lysosomes, resulting in cellular dysfunction. This autosomal recessive disorder has an estimated incidence of 1 in
100,000 to 200,000 live births, which translates into approximately 15 new cases diagnosed each year in the United States. The CTNS gene,
which is located on chromosome 17p13, encodes for cystinosin, a transporter protein responsible for transporting cystine out of the lysosome.
Polyuria, polydipsia, growth failure, rickets, and electrolyte abnormalities manifest in the second half of the first postnatal year in
approximately 95% of children who have cystinosis. Cystine accumulation within the proximal tubular cells may result in impaired energy
generation and a subsequent defect in solute reabsorption. Cystine accumulation within the cornea results in intense photophobia, as
described for the child in the vignette. Patients who have cystinosis also may develop hypothyroidism. Cystinosis may be suspected when
cystine crystals are visible within the cornea during slitlamp ophthalmologic examination. The diagnosis is confirmed by the finding of an
elevated white blood cell cystine concentration. Treatment includes replacement of electrolyte losses and oral cysteamine therapy.
Cysteamine is directed at the transport defect in cystinosis and has been shown to prolong renal survival from 10 years in untreated patients
to 23 years when instituted prior to 3 years of age. The practitioner evaluating a child who is failing to thrive should consider electrolyte
measurement and renal function tests when no obvious nutritional cause is present. Polyuria, polydipsia, and nocturnal fluid intake (the child
awakens from sleep to drink fluid) are suggestive of diabetes insipidus, but specific electrolyte abnormalities can indicate the possibility of
Fanconi syndrome. The patient in the vignette is exhibiting failure to thrive, but the electrolyte panel,but the electrolyte panel, which includes
a normal chloride value and metabolic acidosis, is inconsistent with that of a patient who has cystic fibrosis (CF). Patients who have CF
typically have excessive loss of chloride in their sweat that results in hypochloremia and metabolic alkalosis. Patients who have primary
hyperparathyroidism have low phosphorus and slightly low bicarbonate values, but have hypercalcemia. This patient’s normal calcium
concentration and hypokalemia are inconsistent with an abnormality of parathyroid hormone secretion. Urine ammonia measurement can be
useful in patients who have distal renal tubular acidosis, which is associated with normal anion gap metabolic acidosis, but few of the other
electrolyte abnormalities reported for this patient. Urine chloride measurement is useful for those who have Bartter syndrome and Gitelman
syndrome, which could explain the hypokalemia and hypomagnesemia, but these conditions are associated with hypochloremic metabolic
alkalosis, which is not present in the patient in the vignette.

Question 150 Answer: E Hypertension is a major cause of morbidity and mortality in adults, and growing data suggest that it is becoming a
greater clinical problem in the pediatric population, particularly adolescents. Although yet to be defined clearly, the lifelong risks for the child
who has hypertension or a prehypertensive state are likely to be substantial. Blood pressure is affected by height, weight, sex, and race. A
complete medical history, particularly family history and medications (including over-the-counter supplements), and a thorough physical
examination are essential to early and accurate diagnosis of hypertension and assessment of its secondary causes, comorbidities, and
potential complications. Measurement of the blood pressure is a salient component of the yearly health supervision visit for children beginning
at 3 years of age. When the patient is calm and relaxed, blood pressure should be measured in the right arm with the patient seated and the
arm resting at the level of the heart. The stethoscope should be placed about 2 cm superior to the cubital fossa, just over the brachial artery.
It is extremely important to use the proper size cuff for each patient. The bladder of the cuff (not the cuff material) is the most important
determinant of cuff size. The bladder width should cover 60% to 70% of the upper arm length. The cuff bladder length should cover 80% to
100% of the circumference of the arm to ensure complete compression of the brachial artery during cuff inflation. A cuff that is too small will
result in a falsely elevated reading. A cuff that appears too large will not affect the measurement adversely. Most errors in blood pressure
measurement occur in obese or highly muscularized patients when a cuff is used that is too small. Severe hypertension and hypertensive
crisis should be managed aggressively. The latter typically results from the ingestion of drugs that cause hypertension, injury, or disease of
the kidney or previously unrecognized, progressive hypertension. Symptoms of severe hypertension may include headache, changes in vision,
epistaxis, seizure, pulmonary edema with congestive heart failure, and those that may arise from renal failure.The patient described in the
vignette has a significantly elevated blood pressure that involves marked and reproducible systolic and diastolic hypertension. The best
management plan is to monitor his blood pressure while the cause is ascertained and treatment begun, which involves admission to the
hospital and initial treatment with an intravenous antihypertensive agent. The goal of such therapy is to reduce the blood pressure by 25% or
less over the first 8 hours and gradually normalize it over the next 48 hours to avoid complications (eg, cerebrovascular accident).The choice
of chronic antihypertensive therapy depends, in part, on the cause of the hypertension, but for immediate short-term management,
vasodilators (eg, calcium channel blockers, hydralazine, nitroprusside) are useful. These agents reduce the afterload against which the left
ventricle pumps, thereby reducing its work and oxygen consumption. Alternatively, short-acting beta blockers could be used in the acute
setting. When using beta blockers, however, the clinician must bear in mind their potential complications, including exacerbation of underlying
asthma. Of importance, pharmacologic management of severe hypertension and hypertensive crisis should use medications that can be
titrated to effect readily and have a fast onset of action. Diuretics, particularly the thiazide class, often are used as first-line antihypertensive
agents for those who have mild or moderate hypertension that can be controlled on an outpatient basis. These may be used in combination
with other agents, including but not limited to angiotensin-converting enzyme inhibitors or angiotensin receptor blockers, if adequate control
is not obtained with a single agent. The significant hypertension reported for the boy in the vignette requires immediate action; repeating the
blood pressure measurement in 1 to 2 weeks is not appropriate.

Question 158 Answer: E The child who has asymptomatic, isolated microscopic hematuria is seen frequently in the ambulatory setting.
Results of a urine dipstick test in patients who have hematuria are positive for blood, indicating the presence of hemoglobin or myoglobin. A
microscopic evaluation that reveals more than 5 red blood cells/high-power field, as described for the girl in the vignette, confirms the
presence of hematuria. Because isolated microscopic hematuria has been found in 4% of children on at least one of four tested samples,
evaluation is not recommended unless hematuria is present on at least two of three urine samples. Accordingly, the girl in the vignette should
undergo repeat urinalysis in 2 weeks. The prevalence of hematuria in two of three samples is 1% in females and 0.5% in males.Red blood
cells in the urine may arise from the kidney (glomerular or nonglomerular), ureter, bladder, or urethra. Persistent hematuria demands
evaluation. It is customary to evaluate renal function by measuring blood urea nitrogen and creatinine and to obtain a complete blood count
and platelet measurement (looking for thrombocytopenia as a possible a possible cause) and an erythrocyte sedimentation rate (looking for
an underlying inflammatory cause of hematuria). In addition, serologic tests, including complement components 3 and 4, antinuclear
antibody, and anti-double-stranded DNA, are recommended to look for markers of immune complex-mediated glomerulonephritis, which can
be seen with postinfectious nephritis, membranoproliferative glomerulonephritis, and lupus nephritis. Recommended urine studies consist of
urinalysis with microscopy, urine protein and creatinine measurement, and urine culture. Measurement of a urine calcium-to-creatinine ratio
is advocated by some but is not universally supported. Finally, abdominal computed tomography scan is not indicated in teh evaluation of the
patient who has isolated hematuria. This test may be helpful in identifying renal tumors, but these neoplasms usually can be diagnosed by
ultrasonography.The absence of symptoms in children who have isolated microscopic hematuria allows the practitioner to defer urgent
evaluation because the likelihood of an underlying systemic disease or a disease limited to the urinary tract that warrants urgent attention is
low. Similarly, patients who have microscopic hematuria unaccompanied by proteinuria are unlikely to have a significant disruption of the
glomerular capillary barrier. On the other hand, if a child is asymptomatic but has hematuria and proteinuria, evaluation should proceed
promptly, looking for an underlying renal parenchymal disorder such as glomerulonephritis. Cystoscopy rarely is indicated in pediatrics, and
the decision to pursue this invasive evaluation should be made by a pediatric urologist.

Question 173 Answer: E The differential diagnosis for an infant who has hydronephrosis in the first postnatal year includes ureteropelvic
junction (UPJ) obstruction, ureterovesical junction (UVJ) obstruction, single-system ureterocele, vesicoureteral reflux (VUR), and posterior
urethral valves (usually causes bilateral hydronephrosis). If hydronephrosis is found on renal/bladder ultrasonography, voiding
cystourethrography (VCUG) is undertaken to rule out VUR and assess for a filling defect in the bladder caused by a ureterocele (Item C173A).
Following VCUG, a technetium-99m mercaptoacetyltriglycerine (MAG-3) radioisotope scan with furosemide is performed to assess for UPJ
obstruction. If UPJ obstruction is present, the radioisotope exhibits delayed washout. During the test, furosemide is infused and may
precipitate an episode of renal colic, as reported for the infant in the vignette. If a UPJ obstruction is diagnosed, the practitioner should
contact a pediatric nephrologist or urologist to help with further management. A duplex collecting system with a ureterocele is detected by
VCUG that reveals a filling defect in the bladder and VUR (in approximately 50% of cases). On ultrasonography, a multicystic dysplastic
kidney (MCDK) (Item C173B) exhibits multiple large cysts that do not communicate and a rim of dysplastic renal parenchyma. An MCDK
occurs unilaterally and has no inherent function. Obstructive uropathy from posterior urethral valves is characterized by narrowing of the
posterior urethra (Item C173C) and is associated with bilateral hydronephrosis in nearly all cases and VUR in approximately 50% of cases.
Nephrolithiasis is defined acalculus within the renal parenchyma. Ultrasonography may reveal a calculus. Only if the calculus moves into the
collecting system would hydronephrosis or renal colic following a diuretic renal scan occur. A calculus within the collecting system is known as

Question 188 Answer: B A palpable abdominal mass in the newborn usually is related to the kidney. The most common lesions responsible
are multicystic dysplastic kidney (MCDK) and hydronephrosis due to ureteropelvic junction (UPJ) obstruction. Anomalies such as MCDK are
detected either on in utero ultrasonography or postnatally as an abdominal mass. On ultrasonography, the lesion is associated with large
renal cysts that are noncommunicating (Item C188A). An MCDK is a nonfunctioning nephron unit; a patient who has a unilateral MCDK and a
normal contralateral kidney is considered to have a single kidney. The incidence of MCDK is estimated at 1 in 4,000 live births. An additional
important aspect of MCDK is that vesicoureteral reflux (VUR) occurs in approximately 30% of cases into the functioning, contralateral kidney.
Also, approximately 15% of contralateral kidneys may have a component of obstruction. The standard approach to an infant in whom a
unilateral MCDK is diagnosed begins with the institution of prophylactic antibiotics (based on the 30% risk of VUR in the contralateral kidney).
Voiding cystourethrography and a diuretic renal scan (DRS) should be obtained. The DRS generally demonstrates normal uptake by the
"healthy" contralateral kidney and absence of uptake in the region of the nonfunctioning MCDK. If not diagnosed by in utero ultrasonography,
hydronephrosis may present as an abdominal mass in the newborn period. The most common cause is UPJ obstruction. More rarely, it is
caused by ureterovesical junction (UVJ) obstruction, single-system ureterocele, or VUR. The approach to a patient in whom hydronephrosis is
suspected begins with renal/bladder ultrasonography to confirm the hydronephrosis and screen for other lesions while assessing the
contralateral kidney. Prophylactic antibiotics are recommended, followed by voiding cystourethrography to look for VUR and a technetium-
99m mercaptoacetyltriglycerine (MAG-3) radioisotope scan with furosemide to screen for UPJ or UVJ obstruction. Less common causes of an
abdominal mass in a newborn include gastrointestinal abnormalities (eg, bowel duplication), neuroblastoma, renal vein thrombosis, and Wilms
tumor (rare in this age group).

Question 203 Answer: E A child who has a febrile urinary tract infection (UTI) has a 30% to 50% likelihood of having underlying
vesicoureteral reflux (VUR). VUR is the reflux of urine from the bladder into the ureter and possibly kidney across the ureterovesical junction
(UVJ). It may be caused by anatomic abnormalities of the UVJ or bladder (eg neurogenic bladder) or bladder outlet dysfunction (eg posterior
urethral valves). VUR is estimated to occur 10 times more frequently in Caucasians than in African-Americans. Males and females are nearly
equally affected, and their prognosis is similar. There appears to be a strong familial association for VUR, with approximately 30% of siblings
of an index case also having VUR when studied by voiding cystourethrography (VCUG). Despite this association, screening of asymptomatic
siblings of affected children is controversial because VCUG is an invasive procedure and the benefit of identifying and treating (with
prophylactic antibiotics) a child who is well and lacks symptoms is uncertain. At present, there is no consensus of opinion, although the trend
is not to study asymptomatic older siblings who are toilet trained; some recommend that asymptomatic siblings younger than 1 year of age
undergo VCUG. The American Academy of Pediatrics recommends performing ultrasonography and VCUG in all children after their first febrile
UTI. The present standard of care for patients who have VUR is to receive prophylactic antibiotics until the reflux has resolved. Patients
typically undergo a follow-up VCUG every 12 to 18 months; the time between VCUG studies is somewhat dependent on the age of the patient
and the severity of reflux. An international classification system for VUR has grades ranging from mild (grade I) to severe (grade V). A
nonsurgical approach is recommended for children who have grades I to III reflux; spontaneous resolution occurred in 80% of cases within 5
years of the diagnosis in one study. Grade IV reflux also often is managed nonsurgically. Grade V reflux traditionally has been managed
surgically. A newer technique that involves endoscopic subureteral injection of dextranomer/hyaluronic acid may offer an alternative to
conventional ureteral reimplantation surgery. Long-term data for this technique are not yet available.
Question 209 Answer: C Constipation is defined by infrequent or difficult passage of large or hard fecal material. It occurs commonly in the
pediatric population, and its association with urinary tract dysfunction has been well described. Constipation can cause detrusor instability,
which can lead to urinary incontinence, large bladder capacity, and dyscoordinated voiding. Urinary retention is common, either from
dyscoordinated voiding or from outflow tract obstruction caused by large rectal fecal masses. All of these types of urinary dysfunction can
lead to recurrent urinary tract infections. One study of children who had urinary retention found that 13% had functional constipation as the
cause of their retention. Another found that approximately 30% of chronically constipated children complained of urinary incontinence, and
11% had urinary tract infection. Treatment of the underlying constipation improved urinary incontinence and prevented recurrent urinary
tract infections. The girl described in the vignette is otherwise healthy and growing well, and she has no anatomic urinary tract abnormalities.
Accordingly, treatment of her underlying constipation is the next best step in the prevention of recurrent infections. Fecal disimpaction, stool
softeners, and regular bowel evacuation using timed toilet sitting are the mainstays of treatment. An evaluation for immunodeficiency is not
warranted at this time, but could be considered if her growth parameters were abnormal or if she had additional infections outside of the
urinary tract. Renal scintigraphy is used to assess renal anatomy and function and may be warranted in a child who has recurrent urinary
tract infections, but it is not helpful in preventing future infections. Anticholinergic therapy, such as oxybutynin, can be helpful if overactive or
unstable bladder is suspected, but the girl in the vignette has no symptoms of these conditions. Referral to a pediatric nephrologist may be
indicated if evidence of renal dysfunction is present, but treatment of underlying risk factors, such as constipation, should be initiated first.

Question 211 Answer: A Hypertension is a major cause of morbidity and mortality in adults, and growing data suggest that it is becoming a
greater clinical problem in the pediatric population, particularly adolescents. Although yet to be defined clearly, the lifelong risks for the child
who has hypertension or a prehypertensive state are likely to be substantial. Blood pressure is affected by height, weight, sex, and race. A
complete medical history, particularly family history and medications (including over-the-counter supplements), and a thorough physical
examination are essential to early and accurate diagnosis of hypertension and assessment of secondary causes, comorbidities, and potential
complications. Specific questions in the history should seek to identify clinical findings that might suggest an underlying systemic disorder,
including the presence of gross hematuria, swelling or edema, shortness of breath, or rashes. The past medical history should focus on prior
hospitalizations, previous trauma, and urinary tract infections. The family history should evaluate for hypertension, diabetes, obesity, stroke,
and renal disease. In addition, the history should explore the possibility of medications or drugs (prescribed, illicit, or over-the-counter) that
can be associated with hypertension. An example of the latter may be the use of pseudoephedrine as a nasal decongestant. Additionally,
some families and adolescents use dietary supplements, vitamins, herbal remedies, and homeopathic preparations. Some of these
"supplements" may be associated with sympathomimetic or hypertensive effects. The laboratory and diagnostic evaluation of the child who
has hypertension should be guided by findings on the history and physical examination. For the pediatric patient who has confirmed
hypertension, a screening panel of electrolytes, blood urea nitrogen, and creatinine as well as urinalysis and culture are indicated. Such blood
tests are obtained to rule out renal disease. A urinary drug screen is indicated if the history or patient behavior suggests a possible
contribution by illicit substances, drugs, or supplements that can be associated with hypertension. The child described in the vignette is
overweight, but he has no historical or physical examination findings suggestive of the use of illicit substances, drugs, or supplements.
Echocardiography also is not necessary at this stage of diagnosis because there is no evidence of congenital heart disease such as coarctation
or end-organ involvement. Pediatric patients who have comorbid factors such as diabetes or systemic lupus erythematosus should undergo
echocardiography as part of their hypertension evaluations. Radionuclide imaging of the kidneys involves exposure to ionizing radiation and
typically is reserved for children of this age whose blood pressures are more than 5 mm Hg greater than the 99th percentile. Although renal
vascular ultrasonography does not involve ionizing radiation, it also generally is reserved for young children whose blood pressures are
beyond the 95th percentile and older children and adolescents whose blood pressures exceed the 99th percentile.

Question 218 Answer: B Escherichia coli is the causative organism in 80% to 90% of first-time urinary tract infections (UTIs) in children.
Other pathogens include Klebsiella pneumonia, Proteus sp, Enterococcus sp, and Staphyloccus saprophyticus. Pseudomonas also can be a
pathogen in immunocompromised patients or those who have received repeated courses of antibiotics for recurrent infections. The clinician
must assess the patient for a UTI based on signs, symptoms, and urinalysis findings. Organisms such as E coli, K pneumoniae, and Proteus sp
can reduce dietary nitrate to nitrite, so a positive urine dipstick test for nitrite, as reported for the girl in the vignette, is virtually diagnostic of
gram-negative bacteruria. If the test result is negative in an older child in whom a UTI is suspected, the infection may be caused by a gram-
positive organism such as Enterococcus sp or S saprophyticus. Of note, the nitrite test is much less helpful in infants. Conversion of nitrate to
nitrite may take up to 4 hours. Because infants and young children have small bladder volumes and urinate frequently, there may be
insufficient time for nitrites to be formed and, therefore, the nitrite test may be negative even in the presence of a UTI caused by a gram-
negative organism. Urine pH also may be useful in diagnosing UTIs. Urease-producing organisms (eg, Proteus mirabilis, some strains of S
saprophyticus) degrade urea into ammonia, resulting in an elevated urine pH (8.0 to 8.5). The girl described in the vignette has symptoms of
a lower UTI. Options for therapy include trimethoprim-sulfamethoxazole (if local resistance patterns indicate low levels of E coli resistance) or
a third-generation cephalosporin (eg, cefixime, cefdinir). These antibiotics also may be used for outpatient management of acute
pyelonephritis. For hospitalized patients, a third-generation cephalosporin such as ceftriaxone or cefotaxime provides adequate coverage. An
alternative regimen is ampicillin plus gentamicin.

Question 233 Answer: E The fever, chills, vomiting, abdominal pain, dysuria, and costovertebral angle tenderness described for the girl in
the vignette suggest acute pyelonephritis. Laboratory evaluation demonstrates leukocytosis and abnormal urinalysis findings of hematuria,
proteinuria, positive leukocyte esterase, positive nitrite, pyuria, and bacteriuria. The initial imaging technique in children who have urinary
tract infections (UTIs) is renal/bladder ultrasonography to identify anatomic abnormalities, such as hydronephrosis, renal cysts,
nephrolithiasis, urolithiasis, ureteral dilatation, duplex collecting system, bladder wall thickening, and ureteroceles. Following renal/bladder
ultrasonography, a child who has a first febrile UTI should undergo voiding cystourethrography (VCUG) to screen for the presence of
vesicoureteral reflux (VUR), which typically is present in approximately 30% of patients who experience their first UTI. There are two forms of
cystography: fluoroscopic VCUG and radionuclide cystography (RNC). The fluoroscopic VCUG provides more detailed assessment of the reflux
severity and reveals much more anatomic detail of the bladder and urethra. Therefore, males who have a first-time UTI must undergo
fluoroscopic VCUG initially to rule out posterior urethral valves. Females for whom there are concerns of possible dysfunctional voiding also
should undergo a fluoroscopic VCUG to assess bladder capacity and bladder emptying. Other patients and those previously found to have
normal bladder and urethral anatomy by fluoroscopic VCUG may be evaluated by RNC, which is associated with reduced radiation exposure.
Abdominal computed tomography has a limited role in evaluating patients who have acute pyelonephritis. It is most useful when the child is
not improving despite appropriate antibiotic treatment and concern exists for a renal abscess. Cystoscopy (useful for stone removal or
incisional treatment of a ureterocele). Mercaptoacetyltriglycine (MAG-3)-Tc99 nuclear medicine renal imaging with furosemide (which may
detect ureteropelvic junction obstruction), and intravenous pyelography have no role in the evaluation of a child who has a history of acute
pyelonephritis. Another nuclear medicine scan, dimercaptosuccinic acid (DMSA)-Tc99, can identify regions of hypoperfusion within the renal
parenchyma that occur in acute pyelonephritis or as a result of chronic renal scarring. However, its use generally is limited to those patients
in whom uncertainty about the diagnosis of acute pyelonephritis exists.

Question 241 Answer: D Hypertension may be caused by medications, including over-the-counter preparations, dietary supplements, and
illicit drugs. Essential, or primary, hypertension has no identifiable cause, but secondary hypertension results from an underlying condition,
disorder, drug, or other stimulus. Among the agents that can cause hypertension are corticosteroids, estrogens such as those in contraceptive
therapy, migraine medications, nasal decongestants, and cyclosporine. Over-the-counter preparations that can be associated with
hypertension include the many medications used for relief of cough, cold, and runny nose. Substances of abuse that can cause hypertension
include alcohol, amphetamines, cocaine, and Ecstasy (MDMA and its derivatives). The patient described in the vignette has tachycardia and
hypertension, with both the systolic and diastolic pressures being higher than the 95th percentile. Other important findings in the history
include a relative weight loss from the 50th percentile at age 14 to the 25th percentile (3.5 kg/7 lb) at age 15 years. It is essential to obtain
more detailed information regarding the family history, past medical conditions, hospitalizations, and medication use. The patient confirms the
use of over-the-counter cold remedies, some of which are known to be associated with hypertension as well as vitamins. She should be asked
for further information about these substances. Because this is her first documented episode of hypertension, neither an evaluation for
pheochromocytoma nor computed tomography scan of the abdomen is warranted. Without further information regarding her dietary habits,
there is no indication that she has anorexia nervosa. Similarly, findings on the history are not suggestive of the muscularization or other
physical changes that can be associated with anabolic steroid use.

Question 248 Answer: D The boy described in the vignette has new-onset nephrotic syndrome (NS). The first important step is to establish
the diagnosis based on the presence of severe proteinuria, hypoalbuminemia, and edema. Next, the practitioner must note the child?s blood
pressure (BP) and assess renal function by measuring a serum creatinine because mild degrees of BP elevation and mild azotemia are
consistent with NS, but marked elevations of BP or creatinine are not. In addition, approximately 20% of children presenting with new-onset
NS have microscopic hematuria; gross hematuria should not be present. The next phase of the evaluation involves screening for secondary
causes of NS. Typically, a serologic evaluation includes measurement of complement components (C3 and C4), antinuclear antibody, anti-
double-stranded DNA, hepatitis B surface antigen and core antibody, hepatitis C antibody, and human immunodeficiency virus antibody. A
complete blood count is obtained to look for hematologic abnormalities associated with NS, such as leukemia/lymphoma or sickle cell disease.
A purified protein derivative test is placed to look for occult tuberculosis infection prior to starting treatment. If no secondary cause of the NS
is identified by these tests, the treatment of choice is oral prednisone beginning at 60 mg/m2 per day in divided doses (maximum dose, 40
mg twice per day). The duration of daily therapy is 4 to 6 weeks, after which time the dose is reduced to 40 mg/m 2 (maximum daily dose, 60
mg) on alternate days for 4 to 6 weeks. Recent studies suggest that a longer course (6 weeks daily followed by 6 weeks alternate-day)
results in a higher sustained remission rate than a shorter course (4 weeks daily followed by 4 weeks alternate-day). Although a low-sodium
diet is recommended for children who have new-onset NS, it is adjunctive, not definitive therapy. Diuretics such as furosemide are not
recommended in patients who have NS due to an increased risk of thrombosis. A protein-rich diet has no role in the treatment of NS because
the hypoalbuminemia is due to glomerular losses, not malnutrition. Although allergies can cause periorbital swelling and may be treated with
an antihistamine such as diphenydramine, patients typically exhibit other symptoms, such as rhinitis, sneezing, or conjunctival injection. If
uncertainty exists as to the cause of periorbital swelling and there is concern about possible NS, performance of a urinalysis to detect
proteinuria may be useful.

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