rickets

RICKETS

Physiological action of Vitamin D

Sources Fish Liver Oils Egg yolk Butter Milk

Recommended daily allowance: Infants 200 IU per day Children 400 IU per day

Changes in Deficiency of Vitamin D Biochemical Changes Absorption of calcium from gut decreased

leading to hypocalcemia. Compensatory increase of parathormone

occurs. Helps in release of calcium from osteocytes. Parathormone also reduces excretion of

calcium by kidney and renal tubular reabsorption of phosphate.

Resulting in normal serum calcium level and decrease serum phosphate level.

After some time, decompensation occurs resulting in low level of both calcium and phosphorus.

Since calcium phosphate is needed for calcium deposition in bone, decrease of calcium and phosphate level interferes with calcification of osteoid tissue.

Compensatory increase in osteoblastic activity results in elevation of serum alkaline phosphate level.

Amionaciduria is commonly associated. Serumbircarbonate and serum chloride are

decreased in late stages.

Skeletal Changeso In rickets, process of proliferation,

degeneration and proliferation is incomplete.o Capillary penetration is patchy, cartilage cells

are not degenerated and reabsorbed, proliferation is irregular and calcification is incomplete.

o Bone becomes less rigid.o As the child bears weight, soft metaphyseal

end is compressed leading to flaring .o In subperiosteal region, calcium deposition

surrouding shaft is impaired.o Consequently, shaft bones becomes rarefied

and soft leading to easy fractures and deformities.

Clinical Manifestations of Rickets Craniotabes (abnormal softening of skull).

Seen mostly in occipital bone & posterior part of parietal bone. Bone is soft and has a ping pong ball like feeling on pressing. Large anterior fontaneles, closure delayed beyond 18 months

Bossing of frontal and parietal bones, after 6 months causing rachitic rosary

Pigeon breast Harrison’s groove Scoliosis, kyphosis and lordosis Wide wrist and bow legs Pot-belly, visceroptosis and lumbar lordosis

Findings in Patients with Rickets

Rachitic Rosary and Bow Legs

Diagnosis Clinical manifestations Radiological picture

Lower ends of radius and ulna affected. Cup shaped/saucer-like depression at growing

end of bone. Widened epiphyseal plate. Large gap between epiphysis and metaphyses.

Biochemical findings. Serum calcium may be low or normal. Alkaline phosphate is high (>500mg/dL). Serum phosphate is low (<4mg/dL)

Radiological Picture

Managements Administration of 600000 IU of vitamin D3

orally of IM. Repeat if not heal within 3-4 weeks. If heal, admin 400 IU per day.

Osteotomy. Encouraged outdoor activity for longer

period. High vitamin D3 diet.

Primary Hopophosphatemia (X-linked Vitamin D Resistant Rickets) Transmitted in X-linked dominant fashion. Defect occurs in proximal tubular

reabsorption of phosphate and in in conversion of 25(OH)D3 to 1,25 (OH) 2 D3.

Urinary phosphate excretion increased.

Symptoms Short stature Waddling gait Bow legs Coxa vara (hip deformity where angle between

the ball and the shaft of the femur is reduced to less than 120 degrees)

Genu valgum (knock knees) Abnormal enamel of teeth

Genu Valgum and Waddling Gait

Biochemical Analysis Serum calcium is low or normal Phosphorus is reduced Alkaline phosphate is elevated Aminoaciduria, glycosuria and bicarbonaturia

absent

Vitamin D Dependent Rickets Known as pseudovitamin D deficiency. Occurs even when level of vitamin D in diet is

normal. Type 1 autosomal recessive disorder. Enzyme activity of 25(OH)D3-1alpha-hydroxylase is

deficient resulting in low level of 1,25(OH)2D3 even in hypocalcemia, hypophosphatemia and high parathormone level.

Treat with massive dose of vitamin D2(1 millionU) Fail to be treated is labelled as vitamin D dependent

rickets type 2. Defect is in marked reduction of binding of 1,25(OH)

2D3 to nuclear receptor and nuclear translocation. Symptoms include short stature and alopecia.