0521779407-16 CUNY1086/Karliner 0 521 77940 7 June 4, 2007 21:18
Osteomalacia and Rickets 1101➣Hypophosphatemia and osteomalacia in adults: fractures and
muscle weakness; may resemble late onset X-linked hypophos-
phatemia
■Hereditary causes:
➣X-linked hypophosphatemic rickets:
➣Mutation of Phex gene
➣Phosphaturia due to renal phosphate wasting
➣Hypophosphatemia
➣Relatively deficient in 1,25-dihydroxy vitamin D
➣X-linked or sporadic
➣Can have late onset
■1-alpha-hydroxylase deficiency (vitamin D-dependent rickets,
type I):
➣Mutations in 1-alpha-hydroxylase gene
➣Inadequate conversion of 25- to 1,25-dihydroxy vitamin D
➣Hypocalcemia
➣Hypophosphatemia
➣Secondary hyperparathyroidism
➣Normal 25-hydroxy vitamin D
➣Deficient 1,25-dihydroxy vitamin D
■Hereditary vitamin D-resistant rickets (HVDRR, vitamin D-depen-
dent rickets, type II):
➣Mutations in the vitamin D receptor
➣Elevated 1,25-dihydroxy vitamin D
➣Hypocalcemia
➣Hypophosphatemia
➣Secondary hyperparathyroidism
➣May have alopecia
management
What to Do First
■Assess severity of rickets and hypocalcemia
■Obtain family history
■Assess growth of children
■Perform routine lab tests and imaging
■Assess kidney function
General Measures
■Infants and children susceptible to pneumonia because of poor chest
wall movement; consider chest-x-ray and treatment of pneumonia
if present