Abstracts

Rationale: Enzyme inducing anti epileptic medications (AEDs) are known to be associated with disordered mineral metabolism and osteoporosis. It is hypothesized that the principal effect of AEDs is increased vitamin D metabolism from hepatic P450 hydroxylase enzyme induction. The current “gold standard” for measurement of bone mass is dual energy X ray absorptiometry (DEXA). In this study we review results of 25 hydroxy vitamin D levels and DEXA findings to determine whether one or both these tests are required to screen for bone disease in patients with epilepsy. Methods: 25 Hydroxy-vitamin D levels were measured and DEXA scans performed in 72 ambulatory epileptic subjects who presented to our center over the last 5 years. Vitamin D deficiency was defined as levels < 20 ng/ml. Vitamin D levels were measured within 6 months of DEXA imaging. Subjects were classified into three groups based on DEXA results: normal (group I), osteopenia (group II) and osteoporosis (group III). All statistical calculations were made using SAS software.Results: Mean age was 48.25 years. There were 33 female subjects. Mean 25 hydroxy vitamin D levels were calculated for each group with a mean of 25.88 ng/ml for the normal DEXA group (n= 44), 27.38 for the osteopenic group (n= 19) and 25.7 for the osteoporotic group (n=7). There was no significant difference between the three means or medians using ANOVA as also using non parametric methods.Conclusions: In this study we demonstrate that patients with epilepsy with normal bone mineral densities and those with osteopenia and osteoporosis all share similar mean 25 hydroxy vitamin D levels. Additionally there was no significant difference between the mean vitamin D levels in the three groups suggesting that vitamin D levels may not reflect abnormalities on bone density scans. It is therefore important to use DEXA results as well as serum Vitamin D levels to effectively evaluate bone health in patients currently on anti epileptic drugs.