Analysis of the musculoskeletal system in children and adolescents receiving anticonvulsant monotherapy with valproic acid or carbamazepine.

OBJECTIVE To examine bone development in children and adolescents who have uncomplicated idiopathic epilepsy and had received monotherapy with carbamazepine or valproic acid for at least 1 year. METHODS Thirty-nine patients from 6 to 19 years of age (18 girls) were studied. Total bone mineral content (BMC) and trabecular volumetric bone mineral density were measured at the distal radius using peripheral quantitative computed tomography. Maximum isometric grip force was determined with a standard dynamometer. Alkaline phosphatase activity and deoxypyridinoline (a marker of bone resorption) were assessed in serum and urine, respectively. RESULTS Trabecular volumetric bone mineral density was significantly decreased in the entire group (z score mean +/- standard deviation: -0.62 +/- 1.04) and in the subgroup using valproic acid (-0.75 +/- 1.18). In the carbamazepine subgroup, there was a similar but nonsignificant trend (-0.50 +/- 0.90). Total BMC and isometric maximum grip force were normal in the entire study population (0.10 +/- 1.22) and in the 2 subgroups. The relationship between BMC and grip force was similar between patients and healthy participants. Urinary levels of deoxypyridinoline were significantly elevated above normal in the whole study population (1.35 +/- 2.00) and in both the valproic acid and the carbamazepine subgroups. CONCLUSIONS Bone turnover can be increased, but bone mass is adequate in children and adolescents who have uncomplicated idiopathic epilepsy and who receive monotherapy with carbamazepine or valproic acid.