Effect of carbamazepine therapy on vitamin D and parathormone in epileptic children

Evidence suggests that carbamazepine affects bone metabolism by altering vitamin D status. We prospectively compared 25-hydroxyvitamin D, parathormone, calcium, phosphorus, and alkaline phosphatase levels at initiation and 6 months of carbamazepine therapy in children, and correlated them with carbamazepine levels. We included 47 children newly diagnosed with partial epilepsy, initiated on carbamazepine therapy. Of these, 32 were studied for 6 months. Children were managed according to standard protocol. Various parameters were measured at initiation and at 6 months. Carbamazepine levels were estimated after 6 months. Mean age was 6.72 ± 2.22 years S.D. Mean 25-hydroxyvitamin D was 14.45 ± 9.77 ng/mL S.D. and 11.31 ± 9.15 ng/mL S.D. at baseline and 6 months (P = 0.023), respectively (21.7% decline). Mean parathormone increased from 34.24 ± 21.38 pg/mL S.D. to 45.01 ± 24.46 pg/mL S.D. (P = 0.001). Change in vitamin D correlated negatively with change in parathormone (r = -0.404, P = 0.022). Serum alkaline phosphatase increased from 283.50 ± 100.10 IU/L S.D. to 364.25 ± 126.98 IU/L S.D. (P < 0.001). Changes in vitamin D and parathormone did not correlate significantly with carbamazepine level. Carbamazepine therapy decreased levels of vitamin D. Hence vitamin D monitoring and supplementation may help prevent alterations in bone metabolism.