Synonym: antiepileptic drug induced osteopathy
Features of anticonvulsant-related osteomalacia:
(1) long-term therapy with one or more anticonvulsants, particularly phenytoin and valproic acid
(2) hypocalcemia
(3) low serum 25-hydroxy vitamin D
(4) elevated serum alkaline phosphatase levels
(5) elevated serum parathyroid hormone levels
(6) low bone mineral content and bone mineral density
(7) increased fractures
(8) exclusion of other explanations for osteomalacia
(9) response to therapy with large doses of vitamin D
Possible mechanisms:
(1) hypovitaminosis D secondary to altered metabolism of vitamin D
(2) decreased absorption of calcium from the gastrointestinal tract
(3) direct effect on bone unrelated to vitamn D deficiency (Andress et al)
(4) secondary hyperparathyroidism
