Chronic antiepileptic monotherapy, bone metabolism, and body composition in non-institutionalized children

AIM: The aim of this study was to determine the influence of chronic monotherapy with antiepileptic drugs (AEDs) on vitamin D levels, bone metabolism, and body composition.

METHOD: Eighty-five children (38 males, 47 females; mean age 12 y 5 mo, SD 3 y 4 mo) were treated with valproate and 40 children (28 males, 12 females; mean age 11 y 10 mo, SD 3 y) were treated with other AEDs (lamotrigine, sulthiame, or oxcarbazepine), comprising the non-valproate group. Forty-one healthy children (29 males 12 females; mean age 12 y 1 mo, SD 3 y 5 mo) served as a comparison group. Height, weight, body impedance analysis, 25-hydroxyvitamin D, calcium, phosphate, two bone resorption markers (receptor activator of nuclear factor kappaB ligand [RANKL] and tartrate-resistant acid phosphatase 5b [TRAP5b]), osteoprotegerin, and leptin were measured.

RESULTS: No child was vitamin D deficient as defined by a 25-hydroxyvitamin D (25OHD) level of less than 25 nmol/l (<10 ng/ml). Leptin, body fat, weight standard deviation score (SDS), and body mass index (BMI) SDS were all significantly higher (each p<0.001) in valproate-treated children than in the non-valproate group, as were calcium (p=0.027) and RANKL (p=0.007) concentrations. Similarly, leptin was significantly higher in the valproate group than in control participants (p<0.001), as were body fat (p=0.023), weight SDS (p=0.046), BMI SDS (p=0.047), calcium (p<0.001), and RANKL (p<0.001), whereas TRAP5b concentrations were significantly lower in the valproate-treated group (p=0.002). Furthermore, calcium and RANKL levels were significantly higher in the non-valproate group than in comparison participants (p<0.001 and p=0.016 respectively).

INTERPRETATION: Non-enzyme-inducing or minimal enzyme-inducing AED monotherapy does not cause vitamin D deficiency in otherwise healthy children with epilepsy. Valproate therapy is associated with increases in weight, body fat, and leptin concentration, as well as with a bone metabolic profile that resembles slightly increased parathyroid hormone action.