Decreased serum 24,25-dihydroxyvitamin D concentration during long-term anticonvulsant therapy in adult epileptics.
Serum concentrations of 25-hydroxyvitamin D (25-OHD), 24,25-dihydroxyvitamin D [24,25-(OH)2D], and 1 alpha, 25-dihydroxyvitamin D [1, 25-(OH)2D] were measured in 30 ambulatory adult epileptic patients during long-term anticonvulsant treatment with phenytoin, phenobarbital, or carbamazepine. For the entire group, serum 24,25-(OH)2D was decreased (p less than 0.0005) as compared to normal subjects to a mean value of 0.7 +/- 0.1 (SEM) ng/ml. However, serum 1, 25-(OH)2D was increased at 50 +/- 7 pg/ml (p less than 0.025). Serum 25-OHD declined insignificantly to 19 +/- 3 ng/ml. All three drugs caused a significant reduction of serum 24,25-(OH)2D concentrations. A significant decrease in serum 25-OHD was observed only for the phenobarbital-treated patients. Serum 1, 25-(OH)2D was high in patients receiving phenytoin or carbamazepine but not in those taking phenobarbital. The findings suggest that while various anticonvulsant drugs appear to exert different effects on vitamin D metabolism, a universal finding is diminished serum 24,25-(OH)2D. The results support the notion that 24,25-(OH)2D deficiency may play an important role in the pathogenesis of anticonvulsant-induced osteomalacia.
D000293:Adolescent; D000328:Adult; D000927:Anticonvulsants / Q000009:adverse effects*; D002112:Calcifediol / Q000097:blood; D002117:Calcitriol / Q000097:blood; D002220:Carbamazepine / Q000009:adverse effects; D004872:Ergocalciferols / Q000031:analogs & derivatives* / Q000097:blood; D006801:Humans; D008875:Middle Aged; D010634:Phenobarbital / Q000009:adverse effects; D010672:Phenytoin / Q000009:adverse effects
D000927:Anticonvulsants; D004872:Ergocalciferols; D002220:Carbamazepine; D010672:Phenytoin; C028140:24,25-dihydroxyvitamin D2; D002117:Calcitriol; D002112:Calcifediol; D010634:Phenobarbital