Does carbamazepine treatment lead to a need of extra vitamin D in some mentally retarded children?

Biochemical parameters of vitamin D metabolism were measured in late winter among 40 institutionalized mentally retarded patients. Twenty of them had carbamazepine as their only antiepileptic drug, while the 20 remaining patients had no antiepileptic drugs. Serum calcium and 25-hydroxyvitamin D were significantly lower and alkaline phosphatase significantly higher in patients with than without carbamazepine. Supplementation of the diet with vitamin D in carbamazepine-treated patients abolished the differences. A possibility of hypovitaminosis D should be considered in patients on a long-term carbamazepine therapy, especially if other risks for vitamin D deficiency exist.