Abstracts

Rationale: People with epilepsy are at risk for abnormal bone mineralization. While the etiology for this is not clear, some of the risk is likely related to abnormal vitamin D levels, which may be exacerbated by the hepatic enzyme induction of many of the anticonvulsant medications. Studies have reported variable changes in bone mineral density and vitamin D levels in children taking antiepileptic drugs (AEDs). However, few have examined cohorts of children with epilepsy who are treated with newer AEDs. We aimed to describe the prevalence of, and risk factors for, vitamin D insufficiency among children with epilepsy treated in a general pediatric neurology clinic. Methods: Children 3-to-17 years of age with epilepsy, treated by the authors, were screened on a clinical basis for hypovitaminosis D between September 2008 and March 2009. These patients’ charts were reviewed and vitamin D levels and risk factors were evaluated with multiple logistic regression. Analyses used a dichotomous outcome of 25-hydroxy vitamin D (25OHD) less than or greater than 25ng/ml, the normal value in our laboratory. We examined multiple potential risk factors, including epilepsy type, seizure control, AED regimen (specific medications, polypharmacy vs. monotherapy, duration of treatment), cerebral palsy, ambulatory status, intellectual disability, body mass index (BMI), gender, and ethnicity. Results: 78 patients (41% male, 81% Caucasian) with mean age 11.64±4.37 years were included. Thirty-eight (49%) had generalized epilepsy syndromes and 40 (51%) had localization-related epilepsy. Twenty-three (29%) had idiopathic, 20 (26%) cryptogenic, 35 (45%) symptomatic epilepsies. Seventeen (22%) were treated with old AEDs (e.g. carbamazepine, phenobarbital, valproate), 28 (49%) new AEDs (e.g. lamotrigine, levetiracetam, oxcarbazepine, topiramate, zonisamide), and 23 (29%) took a combination of old and new AEDs. The mean 25OHD level was 28.37±14.13ng/ml and 31 patients (42%) had 25OHD levels <25ng/ml. Multiple logistic regression demonstrated significantly increased odds of low 25OHD levels (<25ng/ml) associated with female gender (odds ratio, OR, 4.07 compared to males, 95% confidence interval, 1.18-13.97), partial epilepsy syndromes (OR 4.53, 1.41-14.60, compared to generalized epilepsy syndromes), as well as increasing BMI (OR 1.179, 1.047-1.329, for each unit increase in BMI). There was no significant difference in 25OHD levels among those taking newer AEDs compared with those treated with older drugs.