MEDICAL MANAGEMENT OF
RENAL STONES
KIDNEY STONES Introduction
This disease is not
transmittable.
Kidney stones can develop
when certain chemicals in
urine form crystals that stick
together.
Stones may also develop
from a persistent kidney
infection.
Drinking small amounts of
fluids.
More frequent in hot weather
SYMPTOMS
Pain in the lower back part or in the lower abdomen,
which might move to the groin. Pain may last from
hours to minutes.
Nausea, vomiting
Blood in urine
Burning during urination, foul smell in urine, chills,
weakness and fevers for urinary tract infection.
EPIDEMIOLOGY
This disease can be
found anywhere.
This disease can strike
on any age group.
COMPARATIVE INCIDENCES OF FORMS OF
URINARY LITHIASIS
Stone analysis in Percentage
Form of Lithiasis India USA Japan UK
Pure Calcium Oxalate 86.1 33 17.4 39.4
Mixed Calcium Oxalate and 4.9 34 50.8 20.2
Phosphate
Magnesium Ammonium 2.7 15 17.4 15.4
Phosphate (Struvite )
Uric Acid 1.2 8.0 4.4 8.0
Cystine 0.4 3.0 1.0 2.8
Cause of Stone Disease
Supersaturation of urine is the key to stone formation
Intermittent supersaturation - Dehydration
Crystal aggregation
Anatomic Abnormailities – PUJ , MSK
Bacterial Infection*
Defects in transport of Calcium and Oxalate by Renal
epithelia
*E.Coli infection increases matrix content in urine . Proteus
makes urine alkaline
Inhibitors, Promoters of Stone Formation
INHIBITORS PROMOTERS
Inhibits crystal Growth - Bacterial Infection
Citrate – complexes with Matrix
Ca Anatomic Abnormalities –
Magnesium – complexes PUJ obst., MSK
with oxalates Altered Ca and oxalate
Pyrophosphate - transport in renal
complexes with Ca epithelia
Zinc Prolonged immobilisation
Inhibits crystal Aggregation Increased uric acid levels
Glycosaminoglycans i.e taking increased
Nephrocalcin
purine subs– promotes
crystalisation of Ca and
oxalate
?? Nanobacteria – seen
in 97% of renal stones
SOME DISEASES ASSOCIATED WITH
HYPERCALCAEMIA & HYPERCALCIURIA
Hyperparathyroidism Leukemia
Sarcoidosis Lymphoma
Multiple myeloma Myxedema
Hyperthyroidism Adrenal
Insufficiency
Metastatic Malig. Neoplasm's Vit. D Intoxication
TYPES OF KIDNEY / URETER
STONES
OXALATE (CALCIUM OXALATE)
PHOSPHATE
URIC ACID & URATE
CYSTINE
Uncommon Stones
XANTHINE STONES
– Autosomal Recessive – Def. of Xanthine Oxidase leading
to Xanthinuria
DIHYDROXYADENINE STONE
– Def. of enzyme adenine phospo ribosyl transferase
SlLICATE STONES
– Rare in humans - excess intake of Antacid with Mg
Trisilicate
( Mostly in cattle due to ingestion of sand )
MATRIX
- Infection by Proteus - Radiolucent (all calculi have some
amt ( 3%) of matrix but matrix calculus has 65% Matrix
content in calculi)
Uncommon Stones
TRIAMTERENE
– Anti-hypertensive used with hydroclorothiazide – spares
potassium. Mostly found as a nucleus in Ca-oxalate or uric acid
calculus
Indinavir Stones
- Drug to treat AIDS (4 to13%)
Ephedrine or Guifenesin
– Cough medicine - Radiolucent
Stones – Chemical Constituents
Whewelite – Calcium Oxalate Monohydrate – CaC2O4-H2O
Weddelite - Calcium Oxalate dihydrate – CaC2O4-2H2O
Brushite – Calcium Hydrogen phosphate dihydrate – CaHPO4
2H2O
Whitlockite - TriCalcium Phosphate – Ca2(PO4)2
Struvite – Magnesium Ammonium hexahydrate – MgNH4PO4-
6H2O
DD of Radiolucent filling defect on IVU
Must Know Know For Brownie Points
Xanthine Calculus
Uric Acid Calculus
Hydroxyadenine Calculus
Matrix Calculus
Ephedrine Calculus
Sloughed Papilla Infection due to gas
Blood Clots forming Org.
TCC Fungal Ball
Renal Cysts Tuberculoma
Vascular Lesions Malacoplakia
Hypertrophied Papilla
Renal pseudo-tumour
OXALATE (CALCIUM OXALATE)
ALSO CALLED MULBERRY STONE
COVERED WITH SHARP PROJECTIONS
SHARP MAKES KIDNEY BLEED (HAEMATURIA)
VERY HARD
RADIO - OPAQUE
Under microscope looks like Hourglass or Dumbbell shape if
monohydrate and Like an Envelope if Dihydrate
PHOSPHATE STONE
USUALLY CALCIUM PHOSPHATE
SOMETIMES CALCIUM MAGNESIUM
AMMONIUM PHOSPHATE OR TRIPLE PHOSPHATE
SMOOTH MINIMUM SYMPTOMS
DIRTY WHITE
RADIO - OPAQUE
Calcium Phosphate also called ‘Brushite’ appears ‘needle-shaped’
under the microscope
PHOSPHATE STONES
IN ALKALINE URINE
ENLARGES RAPIDLY
TAKE SHAPE OF CALYCES
STAGHORN
Struvite can form ‘stag-horn’ and appear like coffin lid under microscope
CALCIUM PHOSPHATE STONES
Hyperparathyroidism Ca P
Renal Tubular Acidosis K CO2
Medullary Sponge Kidney -
PTH Hormone Promotes renal production of 1-25-dihyroxycholecalciferol – active
Vit.D and also increases absorption of Calcium and decreases Phosphorus
absorption from Kidneys
URIC ACID & URATE STONE
HARD & SMOOTH
MULTIPLE
YELLOW OR RED-BROWN
RADIO - LUCENT (USE
ULTRASOUND)
Under microscope appear like irregular plates or rosettes
pKa of uric acid 5.75 – at this pH 50% of uric acid insoluble.
If pH falls further - uric acid more insoluble
CYSTINE STONE
AUTOSOMAL RECESIVE DISORDER
USUALLY IN YOUNG GIRLS
DUE TO CYSTINURIA -
CYSTINE NOT ABSORBED BY TUBULES
MULTIPLE
SOFT OR HARD – can form stag-horns
PINK OR YELLOW - RADIO-OPAQUE
Under microscope appears like hexagonal or
benzene ring – ask for first morning sample
Surgical Conditions and Stone
Disease
Regional ileitis and Ileal Bypass Surgery
for Obesity can lead to increased
oxalate absorption and stone disease
Ileostomies, in Chr. Diarrhoea with
Bicarbonate loss – systemic acidosis and
acidic urine – increases risk of Uric Acid
stones
HISTORY
A. IS PATIENT DRINKING ENOUGH ?
B. PROFESSION
C. ENQUIRE ABOUT UTI - STONES
D. FAMILY HISTORY
E. LONG ILLNESS - BEDRIDDEN - STONES
MANAGEMENT OF STONES
HISTORY :
A. FIND OUT IF DRINKING ENOUGH LIQUIDS
(NOT DRINKING ENOUGH IMPORTANT CAUSE
OF STONE FORMATION & GROWTH)
Urinary supersaturation of salts in concentrated urine
Atleast drink 3 lts to avoid stone formation
HISTORY (Cont...)
B. ASK ABOUT THEIR PROFESSION
DEHYDRATION - STONES CAN FORM e.g.
MARATHON, NEAR A FURNACE,
BRICK - LAYER, LABOURERS & WEAVERS
TRUCK & BUS DRIVERS
HISTORY (Cont...)
C. ENQUIRE ABOUT UTI STONES
D. FAMILY HISTORY
E. LONG ILLNESS BEDRIDDEN STONES
Zero Gravity state – astronauts on long space flights more
prone to stones
CLINICAL FEATURES
1. PAIN IN 75 % OF THE CASES
“RENAL COLIC” IF SEVERE AND ACUTE
A) KIDNEY STONE
FIXED PAIN IN THE LOIN
B) URETERIC STONE
PAIN RADIATES LOIN TO GROIN
Both Stomach & Kidney supplied by celiac ganglion hence nausea & vomiting
common in renal colic
CLINICAL FEATURES (Contd....)
2) HAEMATURIA
CAN BE FRANK
OR ONLY FOUND ON DIP - STICK OR LAB.
3) PYURIA - IF INFECTION, CAN HAVE PUS IN URINE
ON EXAMINATION
1. ACUTE PRESENTATION
ABDOMEN TENSE AND RIGID
TENDERNESS PRESENT IN THE LOIN
2. IN ROUTINE PRESENTATION
NO FINDINGS IN ABDOMEN
INVESTIGATIONS
1. FULL BLOOD COUNT TO CHECK FOR
ANAEMIA, IF GOING FOR SURGERY
2. SERUM ELECTROLYTES PLUS UREA /
CREATININE / CALCIUM / URIC ACID /
PHOSPHATE
INVESTIGATIONS (Cont...)
3. 24-HOURS URINE FOR ELECTROLYTES
(Only if recurrent stone former)
CALCIUM / OXALATE / URIC ACID /
CYSTINE / CITRATE
INVESTIGATIONS (Cont...)
4. PLAIN KUB X-RAY OF ABDOMEN (Mandatory)
5. IVU (INTRA VENOUS UROGRAM) OR IVP
6. ULTRASOUND (Mandatory)
INVESTIGATIONS
IVU OR IVP - Not Mandatory
1 in 40,000 patients die due to anaphylactic reaction to
contrast
Useful for radio-lucent stones & to detect
Congenital Anomalies in Urinary tracts
INVESTIGATIONS (Cont...)
7. CT – TO LOOK AT UNUSUAL ANATOMY OF THE KIDNEY
To differentiate cause of acute colic – stone or anuria
suspected due to stone disease
8. DMSA OR DTPA OR MAG3 RENOGRAM - TO STUDY FUNCTION
OF EACH KIDNEY.
Bilateral Ureteric Calculus in a patient presenting with Anuria
Helical or Spiral CT provides 3D reconstruction. Helical refers to path the X ray
follows on Gantry. These are rapidly performed and do not require contrast agents
for reconstruction.
MANAGEMENT OF UROLITHIASIS
Non-invasive approach to urinary calculus -
HALLMARK for last 20 yrs.
Lithotripters –
1.Extra Corporeal Shock wave
2.Intra Corporeal
Better fiber optics – Miniaturisation of Telescopes
Accessories - Innovative variety
Diet & Fluid Advice
High Fluid Intake
Restrict Salt (Na)
Oxalate Restrict
Avoid high intake of Purine food
Increased citrus fruits may help
If hypercalciuria restrict Ca intake
Role of Potassium Citrate in preventing Cal Oxalate stone ds – KCit
lowers urinary calcium whereas Na Citrate does not lower Calcium due
to Sodium load
LIQUIDS
Moderate Amounts : High Amounts :
Apple Juice Cocoa
Beer Fresh Tea
Coffee
Cola
FOODS :
Almonds, Asparagus, Cashew Nuts, Currants, Greens,
Plums, Raspberries, Spinach
Principles of Medical Management
Monitor stone burden with periodic KUB
Instruct patient on adequate water
consumption ( enough to produce 2L of urine
in 24 hrs.)
Instruct in low oxalate and modified calcium
diet
If hypercalcuric, treat with
hydrochlorothiazide (monitor urinary Ca)
Principles of Medical Management 2
If hyperuricosuric
– allopurinol if serum uric acid elevated
– alkalinize urine if serum level is normal
If active Ca stone former not aided by diet, HCTZ
added to K-citrate
If magnesium ammonium phosphate stone, after
reduction of burden treat aggressively with antibiotics
Anatomic Evaluation
Necessary to decide on how to best treat
– size and location of stone
– number of stones
– anatomy of kidney, ureter
– is stone overlying bone
– “condition” of involved kidney
Principles of Stone Prevention
Prevent supersaturation
– water! water and more water enough to make 2L
of urine per day
– prevent solute overload by low oxalate and
moderate Ca intake and treatment of
hypercalcuria
– replace “solubilizers” i.e... citrate
– manipulate pH in case of uric acid and cystine
Flush! forced water intake after any dehydration
Urine citrate
Hypocitriuria is one of the most
remarkable Feature of renal tubular
acidosis and kidney stone Formation
Hypocitriuria is a frequent finding in
individuals with Recurrent stone
formation.
Presence of citrate in urine is an
inhibitor of stone formation.
Emergency Department Care
Intravenous access - for analgesics and antiemetics
Intravenous hydration is controversial.
– May hasten passage of the stone
– Others feel exacerbates the pain of renal colic
– IV hydration should be given in dehydration or
with a borderline serum creatinine level who must
undergo IVP
– Strain urine for stone collection
Ref: J Endourol. Oct 2006;20(10):713-6
ED Care – Analgesics Antiemetics
Analgesia should be provided promptly.
– The pain of renal colic is mediated by PGE2.
NSAIDs inhibit formation of this mediator
– NSAIDs have been proven in multiple studies to be
as effective as opioid analgesics, with fewer
adverse effect
– Opioid analgesics can be added in cases of
incomplete pain control
Antiemetics should be administered as needed
Ref: Arch Intern Med. Jun 27 1994;154(12):1381-7
Am J Emerg Med. Jan 1999;17(1):6-10
ED Care - Expulsive therapy
o Multiple prospective randomized controlled studies
in the urology literature have demonstrated that
patients treated with oral alpha-blockers have an
increased rate of spontaneous stone passage and
a decreased time to stone passage
o The best studied of these is tamsulosin, 0.4 mg
administered daily
Ref: J Urol. Dec 2003;170(6 Pt 1):2202-5
J Urol. Jul 2005;174(1):167-72
J Urol. Aug 2004;172(2):568-71
ED Care - Expulsive therapy
o CCBs in combination with oral steroids have also
proven efficacious in multiple studies. The most
common regimen is 30-mg slow-release nifedipine
daily plus oral corticosteroid such as prednisolone
o A systematic review found that medical expulsive
therapy using either alpha antagonists or CCBs
augmented the stone expulsion rate for
moderately sized distal ureteral stones
Ref: Ann Emerg Med. Nov 2007;50(5):552-63
ED Care - Expulsive therapy
– A systematic review found that medical
expulsive therapy with alpha antagonists
for 28 days increased the rate and
decreased the time to stone passage;
decreased the rates of hospitalization and
ureteroscopy
Ref: Ann Pharmacother. Jul-Aug 2006;40(7-8):1361-8
Ca-oxalate, ca-phosphate, and
ca-urate are associated with:
– Hyperparathyroidism - Treated surgically or with
orthophosphates if the patient is not a surgical
candidate
– Increased gut absorption of calcium - The most
common identifiable cause of hypercalciuria,
treated with calcium binders or thiazides plus
potassium citrate
Ca-oxalate, ca-phosphate, and
ca-urate are associated with:
– Renal calcium leak - Treated with thiazide
diuretics
– Renal phosphate leak - Treated with oral
phosphate supplements
– Hyperuricosuria - Treated with allopurinol, low
purine diet, or alkalinizing agents such as
potassium citrate
Ca-oxalate, ca-phosphate, and
ca-urate are associated with:
– Hyperoxaluria - Treated with dietary oxalate
restriction, oxalate binders, vitamin B-6, or
orthophosphates
– Hypocitraturia - Treated with potassium citrate
– Hypomagnesuria - Treated with magnesium
supplements
Struvite (magnesium ammonium
phosphate) stones
Struvite stones are associated with chronic UTI with
gram-negative rods capable of splitting urea into
ammonium, which combines with phosphate and
magnesium
Underlying anatomical abnormalities that predispose
patients to recurrent kidney infections should be
sought and corrected
Struvite (magnesium ammonium
phosphate) stones
– Usual organisms include Proteus, Pseudomonas,
and Klebsiella species
– Escherichia coli is not capable of splitting urea
and, therefore, is not associated with struvite
stones
– UTI does not resolve until stone is removed
entirely
Urine pH is typically greater than 7
Uric acid stones
Associated with urine pH less than 5.5, high purine
intake (eg, organ meats, legumes, fish, meat
extracts, gravies), or malignancy
Approximately 25% of patients with uric acid stone
have gout - serum and 24-hour urine sample should
be sent for creatinine and uric acid determination
If serum or urinary uric acid is elevated, the patient
may be treated with allopurinol 300 mg daily
Patients with normal serum or urinary uric acid are
best managed by alkali therapy alone
Cystine stones
Treated with low-methionine diet (unpleasant),
binders such as penicillamine or a-
mercaptopropionylglycine, large urinary volumes, or
alkalinizing agents
A 24-hour quantitative urinary cystine determination
helps to titrate the dose of drug therapy to achieve a
urinary cystine concentration of less than 300 mg/L
Drug-induced stone disease
A number of medications or their metabolites can
precipitate in urine causing stone formation
These include indinavir; atazanavir; guaifenesin;
triamterene; silicate (overuse of antacids containing
magnesium silicate); and sulfa drugs including
sulfasalazine, sulfadiazine, acetylsulfamethoxazole,
acetylsulfasoxazole, and acetylsulfaguanidine
Ref: Urology. Oct 2003;62(4):748
Urol Clin North Am. Feb 2003;30(1):123-31
Urology. Jan 2004;63(1):175-6
Potassium-magnesium-citrate
Potassium citrate reduces urinary
saturation of calcium by complexing
with calcium in urine and thus reduces
urinary calcium
Citrate also inhibits spontaneous
nucleation of calcium oxalate and
calcium phosphate
Due to its alkalinising effect it increases
dissolution of uric acid and thus reduce
uric acid stone formation
Magnesium
It forms complex with oxalate and reduces
supersaturation of urine with calcium oxalate
It increases pH of urine and thus inhibit stone
Formation
Magnesium has direct inhibitory influence on
Calcium phosphate crystal growth.
Magnesium also prevents intestinal absorption of
Oxalate 1
1. Am J Ther,2006 Mar-Apr ; 13(2) : 101-8
CONCLUSION
As compared to potassium citrate , Potssium –
magnesium citrate cause more
Rise in urinary pH
Rise in urinary citrate level
Rise in urinary magnesium level
Reduction in undissociated uric acid level
Equally effective in correcting thiazide induced
hypokalemia
Potassium magnesium citrate based medical
prophylaxis is effective for preventing
recurrence of urinary stones like calcium
oxalate, hypercalciuria, hyperuricosuria and
hypocitriuria
Regular prophylaxis effectively prevent stone
recurrence regardless of stone composition,
metabolic abnormalities and stone –free
status.
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