Osteomalacia is a group of metabolic bone disorders characterized by decreased bone
mineral density associated with increased osteoid. Causes of osteomalacia can be
classified into three categories defects in metabolism and action of vitamin D, defects in
mineral metabolisms, and disorders of bone cells and matrix. The first category includes
vitamin D deficiency, anticonvulsant-induced osteomalacia, disorders of vitamin D
metabolism in the kidney and hereditary resistance to 1,25(OH)2D. The second includes
calcium and phosphorus deficiency syndromes, X-linked familial hypophosphatemia, renal
tubular injuries, on cogenic osteomalacia and hyperphosphatemic osteomalacia. The third
includes familial hypophosphatasia, low turnover osteomalacia, osteogenesis imperfecta,
axial osteomalacia and drugs inhibiting mineralization. For osteomalacia caused by
vitamin D deficiency, more than five times of daily requirement should be given as
either calciferols or 1,25(OH)2D. For hereditary resistance to 1,25(OH)2D, a huge amount
of 1,25(OH)2D should be administered mostly with calcium. In the cases of calcium or
phsphorus deficiency, a sufficient amount of the minerals should be supplemented.
Oncogenic osteomalacia is completely cured in most cases by removal of tumors
secreting a humoral substande(s) that inhibits renal phosphate reabsorption.
Unfortunately, there is no successful treatment the hereditary disorders that cause a
defect in bone cells or matrix.
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