Rickets

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					Rickets
 Dr Rajesh
  26/09/07
Definition
   Rickets is defined as the failure of
    calcification of osteoid in the growing
    person
Definition
    it is a general disorder of metabolism affecting chiefly the
     growing bones due to deficiency of the active form of
     vit.D “1,25 dihydroxy vit.D” .

    The essential changes of the bones are :
1.   Decalcification of the normal bones.
2.   Formation of imperfectly calcified bone
     1.    widening & enlargement of the epiphyseal end of the long
          bones.

THE SKELETAL MUSCLES &THE NERVOUS
SYSTEM ARE SOMETIMETIMES AFFECTED.
   THERE ARE 2 TYPES OF VIT. D:

1.D3 "CHOLICALCIFEROLE" which is of animal origin and
  produced by action of the U/V on 7-dehydochlesterol in
  the skin.

2. D2 "ERGOSTEROLE" which is of plant origin and
   produced by action of U/V on ergosterol in the plants.

The both types are biologically inactive, so they
   HYDROXYLATED in the LIVER -->25 HYDROXY vit.d
then HYDROXYLATED in the KIDNEYS ---> the final active
   form of vit.D 1,25 HYDROXY VIT.D which called
   CALCITRIOLE.
Vit D actions
1.   Promotes ca & p absorption in small gut .
2.   Increase ca & p reabsorption in the kidneys.
3.   Direct effect of menirals metabolism of bones
     "depositioin & resorption "
Rickets: Symptoms
a. early symptoms "appear b/w 3-6 months " :
    1.head sweating.
    2.irrit. by day & sleepnessness by night.

b. advanced rickets :
  delayed motor development "sitting,
  standing & walking "
Normal bone growth
THERE ARE 4 ZONES :
1.ZONE OF RESTING CARTILAGE : 1 layer
2.ZONE OF PROLIFERATING CART. : 6 layers
3.zone OF PROVISSIONAL CALCIFICATION "epiphyseal line " :
the cart. cells in this layer bere mature, they containe alkaline phosphatase 
   release the phosphate in the matrix which already contains ca. & po4 in
   solution  increase production of ca. & po4  once the production
   exceeds 40  precipitation of ca.phosphate in the matrix around the
   cartilage cells        death of the cells.
4.ZONE OF BONE FORMATION :
The layer of prov. calc. is invaded by capillaries and osteoblast which deposit a
   layer of organic bone matrix "osteoid tis.“  rapidly meniralized and the
   calcified cartilage ultimitly replaced by bone.
THE CHANGES IN INFANTILE RICKETS:
VIT.D DEFICIENCY  decrease absorption of ca. & p from the gut
       decrease ca. level in blood
       increase PTH
       mobilization of ca. & po4 from bones and decrease tubular
      reabsorption of p in kidneys
       normal serum ca. & low serum po4
       decrease ca. available for bones
       ca. & po4 will be far below 40
       failure of calcification around the mature cart. cells
          and osteoblasts in the ostoeid tis.
1.   the mature cartilage cells will not die and the
     proliferating zone will be formed of many layers and
     invades the adjacent zone of of provis. calc. and hence
     the irregularity of epiphseal line in the X-RAY.
2.   the prov. calc. zone and newly formed ost. tis. will
     failed to calcified or will calcified irregularly...
      wide irregular frayed zone of non rigid tis. "
     RACHITIC METAPHSIS " is produced
      flaring of bone & rachitic rosary.
3.   in the shaft the preformed bone is replaced by
     uncalcified ost. tis. from the periosteom ...
            formation of shell surrounding the shaft 
     soft rarified cortical bone
            bone deformities & green stick fractures.
Rickets: signs
   Skull
       Craniotabes, Frontal and parietal bossing, flat
        occiput
   Chest
       Rosary, Harrison’s sulcus, Pigeon chest
   Extremities:
       Widening of wrist, Marphan’s sign at ankle,
        Bowing of legs, Knock knee
Hypotonia and laxity of joints
Delayed motor milestones as sitting & walking.
 Flaccidity of the whole body  hyperextinsibility
 of joints. Smooth kyphosis in the dorso-lumber
 region while sitting
   it is correctable if the pt. suspended from the
   shoulders.
The abdomen is distended “POT BELLY “ due to
  hypotonia of abd. Muscles & intistine .
  downward displacement of the liver & spleen due to :
     1. laxity of their lig. & deformity of chest wall .
     2.hypotonia of the abd. Muscles.
X-Ray
The X-RAYS of the wrists is best for early diagnosis an
   shows:
1.The classic triad of rickets :
    broadening + cupping (concave) + fraying ( irregular) of
   lower ends of radius & ulna .
2.Increase distance between the distal ends of radius &
   ulna and the metacarpal bones .
3.Demeniralization of the shaft “ hypodensity”
4.Fractures & deformities may be present
     LOOSER’S ZONE  linear partial fractures of
  long bones which failed to calcify.
X-Ray
   THE EVIDENCE OF HEALING WILL
    APPEAR IN X-RAY BTWEEN THE 2ND &
    3rd weeks  the line preparatory
    calcification indicate start of healing
Complications of rickets
   TETANY : it is usually precipitated by inf. Due to
    failure of compensatory mechanism.
   RECURR. CHEST INF. : due to
       a. chest wall deformity .
       b. ass. Vit.A deficiency which is essential for integrity of epith.
        Surface of the resp. mucosa.
       c. defective function of immunity system “esp. T-lymph “
 FRACTURES OF BONES.
 DEFORMITIES OF BONES : the most
    important is RACHITIC PELVIS .
Treatment of rickets
   Daily administration of 1000 – 4000 units :  produce
    healing in 2 – 4 weeks & the healing complete in 6 – 8
    weeks .
   alternative method of treatment :oral or IM administration
    of massive dose of vit.D 600.000 IU that should not
    repeated except if there is no evidence of healing in X-
    RAY.
   the prematures in addition to vit.D also ca. & p( 60mg
    elemental ca/day & 30 mg elemental p / day ).
Lab studies
   Calcium: Early calcium (ionized fraction) will be
    low; however, more often, normal at diagnosis.
   Phosphorus: low for age unless recent partial
    treatment or recent exposure to sunlight has
    occurred.
   Alkaline phosphatase: Elevated
   Calcidiol levels are low, and parathyroid
    hormone levels are elevated.
   Aminoaciduria: Occurs from the parathyroid
    activity; aminoaciduria does not occur in familial
    hypophosphatemia rickets (FHR).
Lab:
   Calcium: Increased in Jansen type
   Phosphorus:
       Increased in renal osteodystrophy
       Normal in metaphyseal dysostosis
   ALP:
       Low in hypophospatasia
       Normal in metaphyseal dysostosis
   Aminoaciduria: no in phosphate deficiency
    rickets except fanconi syndrome. No in
    metaphyseal dysostosis
 Rickets: Classification
 1: Calcium deficient              2: Phosphate deficient
  Lack of vit D
                                    Hypophosphatemia
        Lack of sunlight
        Dietary deficiency         Fanconi syndrome

        congenital                 RTA
    Malabsorp of vit D             Oncogenic
    Hepatic disease                  hypophosphetemia
    Anticonvulsants
                                    Phosphate deficiency
    Renal osteodystrophy
    Vit D dependent type 1        4: Conditions mimicking rickets
                                      Hypophospatasia
3: End organ resistance to vit D      Metaphyseal dysostosis
   VDDR type 2                            Jansen
                                          Schmid
Rickets: Classification
   Vitamin D dependent-caused by reduced
    activity of 25 hydroxy alpha-
    hydroxylase(enzyme that activates vitamin
    D)
   Vitamin D deficiency- “classical rickets”
    caused by low endogenous vitamin D
   Vitamin D resistant- defect in tubular
    reabsorption of phosphate
VITAMIN-D–DEPENDENT RICKETS, TYPE 1

   Genetic deficiency (variable) in the enzyme to
    convert calcidiol to calcitriol in the kidney.
   Autosomal recessive, chromosome 12.
   Presentation as nutritional rickets with a more
    variable phosphate concentration.
   Medical therapy: Treatment is calcitriol 0.5-1.5
    mcg/d.
   Also respond to pharmacologic doses of vitamin
    D (5000-10,000 u/d).
RECEPTOR DEFECT RICKETS
(FORMERLY VITAMIN-D–DEPENDENT RICKETS, TYPE II).


   Recessively inherited lack of calcitriol receptor
    sites
   Properly called vitamin-D–resistant.
   50% have alopecia, which sometimes is
    complete.
   Hypocalcemic and usually normophosphatemic.
   Several mutant forms and a wide range of
    severity and of response to calcitriol therapy
    including some totally resistant to therapy.
   May respond to high oral calcium intake plus
    calcitriol.
DEFECTIVE 25-HYDROXYLASE
   Two cases (a single family in the US and
    possibly 1 in Germany) have been reported
    having deficiency of 25 hydroxylase.
   Inheritance probably is autosomal recessive.
   The clinical picture resembles nutritional rickets
    with a later age of onset.
   Treatment with calcidiol in physiologic amounts
    is sufficient. Calcidiol is a natural metabolite of
    vitamin D. It is hydroxylated once at the 25
    position and is the circulating form for vitamin D
    in plasma
FANCONI SYNDROME AND
ONCOGENOUS
   Fanconi syndrome
       E.g. cystinosis and tyrosinemia,
       Renal phosphate wasting along with aminoaciduria
        and glycosuria.
       Responsive to a combination of managing the
        underlying cause when possible and to either vitamin
        D or calcitriol therapy.
   Oncogenous
       Several mesenchymal tumors of bone or connective
        tissue (including those called nonossifying fibromas,
        fibroangioma, and giant cell tumors) secrete a
        phosphaturic substance (parathyroidlike protein) that
        results in rickets.
Osteodystrophy (renal rickets)
   In end-stage renal disease, renal 1-hydroxylase
    is diminished or lost, and there is defective
    excretion of phosphate.
   This leads to hypocalcemia and to failure of
    osteoid calcification;
   Only variety of rickets with a high serum
    phosphate.
   Management of these patients includes a low
    phosphate intake, calcitriol
Hypophosphatasia
   This autosomal recessive
   Absence of alkaline phosphatase
   Causes rickets without disturbance of
    calcium and phosphate metabolism.
   There is a range of clinical expression
    from a severe, even lethal, form to mild
    disturbance. There is currently no useful
    treatment.
METAPHYSEAL DYSPLASIA (SCHMID VARIETY)

   genetic disorder of collagen with the gene
    locus on chromosome 6.
   The appearance of the metaphyses on
    radiographs cannot be distinguished from
    changes seen in rickets
   Osteotomies, if needed, should be
    deferred until growth is complete.
SUN EXPOSURE
   The AAP Committee on Environmental
    Health recommends that infants less than
    6 months of age avoid all sunshine
    exposure (Pediatrics, 104:328- 333.1999)
AAP: Vit D Supplementation
   2003 AAP Recommendation: 200 IU/day
    of Vitamin D for all infants and children
    beginning in the first two months of life
Knock Knees / Genu Valgum
                 Legs are bowed
                  inwards in the
                  standing position.
                  Bowing occurs at or
                  around the knee. On
                  standing with knees
                  together, the feet are
                  far apart.

				
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