Rickets
Rickets results from impaired skeletal mineralization during childhood. It has the same etiologies as osteomalacia in adults in addition to three congenital disorders:
- Hypophosphatemic rickets: deficient renal tubular phosphate reabsorption results in low serum phosphate levels that are inadequate to promote bone mineralization. This is usually X-linked and associated with the PHEX gene. Rarely it can be autosomal dominant and associated with the FGF-23 gene (encoding fibroblast growth factor 23).
- Congenital 1-alpha-hydroxylase deficiency: impaired conversion of 25-OH vitamin D into 1,25 (OH)2 vitamin D causes intestinal calcium and phosphate malabsorption.
- Congenital vitamin D resistance: defective or absent vitamin D receptors result in impaired vitamin D action causing intestinal calcium and phosphate malabsorption.
Clinical manifestations of rickets
Clinical features include bone pain, deformities, fractures, muscle weakness, and growth retardation. Laboratory findings are similar to those in osteomalacia.
x-rays may show delayed opacification of the epiphyses, widened growth plates, widened and irregular metaphyses, and thin cortices with sparse, coarse trabeculae in the diaphyses.
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FIRST YEAR OF LIFE |
AFTER FIRST YEAR OF LIFE |
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Widened cranial sutures |
Flared ends of long bones |
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Frontal bossing |
Bowing of long bones |
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Craniotabes |
Sabre shins |
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Rachitic rosary |
Coxa vara |
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Harrison’s groove |
Genu varum |
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Flared wrists |
Genu valgum |
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