Internal Medicine

0521779407-16 CUNY1086/Karliner 0 521 77940 7 June 4, 2007 21:18

1100 Osteomalacia and Rickets

Signs & Symptoms

■Children: rickets, bowing of long bones, muscle weakness, joint

pains, rachitic rosary

■Adults: osteomalacia, increased susceptibility to bone fracture

tests

Laboratory

■Basic blood tests:

➣Calcium, phosphate, alkaline phosphatase, 25-hydroxy vitamin

D, creatinine clearance

■Specific Diagnostic Tests

➣1,25-dihydroxyvitamin D, parathyroid hormone (PTH), 24-h

urine for phosphate and calcium

Imaging

■Metabolic bone survey: bowing of long bones, widening, cup-

ping, fraying of metaphyses; subperiosteal erosions; pseudofrac-

tures (Looser zones)

■Adults: bone mineral density of hip and spine; bone x-rays for frac-

ture

differential diagnosis

■Nutritional: vitamin D deficiency:

➣Decreased 25-hydroxyvitamin D

➣Hypocalcemia

➣Hypophosphatemia

➣Secondary hyperparathyroidism

■GI disorders/malabsorption syndrome: as nutritional+

➣Signs of malabsorption of other nutrients

➣Diarrhea

■Renal insufficiency:

➣With hypocalcemia and secondary hyperparathyroidism

➣Deficiency of 1-alpha-hydroxylase activity

➣Normal 25-hydroxy vitamin D

➣Deficient 1,25-dihydroxy vitamin D

■Oncogenic osteomalacia:

➣Tumor-induced osteomalacia

➣Usually difficult to find benign mesenchymal tumor

➣Tumor product with renal phosphate wasting and elevated urine

phosphate