Abstracts

Rationale: Chronic antiepileptic drug (AED) administration has been shown to have a negative effect on the bone mineralization process. The complex negative effect of AED on bone homeostasis is multifactorial: AED s cause a direct increase in bone turnover as well as an indirect effect on Vitamin D (Vit D) metabolism via induction of cyp450 enzymes. Reduced bone accumulation during childhood, a critical period of mineralization, can have long-lasting consequences on bone health. Factors such as type of medication and body mass index may influence child s risk of decreased bone density. Methods: A retrospective analysis of a consecutive group of ambulatory pediatric patients evaluated at a specialized epilepsy center was conducted. All patients were on chronic (>1 yr) antiepileptic medication. Thirty two patients had a dual-energy radiograph absorptiometry (DEXA) scans (BMD). The BMI (low: ?18.5, normal: >18.5<25, or overweight:?25), the AED regimen (at least one enzyme inducing medication or no enzyme inducing mediations) and Vit D levels were recorded. Results: Twenty five percent of our cohort was diagnosed with low bone density osteoporosis/osteopenia (?1 SD below the mean for their age group). Of these, about fifty percent were diagnosed with osteoporosis (?2.5 SD below the mean for their age group). Vit D levels did not appear to influence the bone status: 50% of patients with osteoporosis and 80% of patients with osteopenia had low vit D levels vs. 87% of patients with normal BMD. Findings support a protective effect of high BMI on bone status as observed in adult populations. 61% of patients with normal bone density had high BMI (?25), compared to 12% in the osteopenic group and none in the osteoporotic group. 75% of patients with osteoporosis and 20% of patients with osteopenia (about half of the patients with low bone density) had low BMI (?18.5), compared to 9% of patients with normal bone density. AED did not influence the BMD (56% of patients with osteoporosis/osteopenia were treated with enzyme inducing drugs compared to 73% of patients with normal bone density) although their use was associated with low Vit D. Additionally, Caucasian race seemed to be a risk factor for osteoporosis/osteopenia: 60% of osteopenic patients and 100% of osteoporotic patients were white. This finding is consistent with trends in bone density in the adult population. Conclusions: Pediatric patients on antiepileptic medication have a high risk for low bone mass and guidelines for regular evaluation of bone status are necessary. Risk factors for low bone density among pediatric epilepsy patients may include low BMI and Caucasian race. Complex factors directly related to epilepsy as a chronic progressive disease (e.g. chronic oxidative stress) may interfere with the bone homeostasis in addition to the low Vit D and AED s.