Low vitamin D levels are common in patients with epilepsy

Vitamin D is important for bone health, and vitamin D deficiency may contribute to other disorders (e.g., autoimmune, infections, cancer, degenerative, diabetic, and vascular). Enzyme-inducing antiepileptic drugs have been particularly implicated for osteoporosis risk given their effects on vitamin D. We examined the prevalence of vitamin D deficiency in adult epilepsy patients.

We conducted an observational study of consecutive epilepsy patients treated by two clinicians at the Emory University Epilepsy Center from 2008 to 2011 in order to determine the frequency of low vitamin D levels and possible differential antiepileptic drug risks. Vitamin D 25-OH levels were categorized as low (<20 ng/ml), borderline (20-29 ng/ml), or normal (≥30 ng/ml). Antiepileptic drugs were categorized based on their enzyme inducing properties. Descriptive and inferential statistics were employed.

Vitamin D levels were obtained on 596 patients with epilepsy. Mean age was 41 years (SD=14; range=18-81); 56% were women. Race/ethnicity was 55% Caucasian, 34% Black, 2% Asian, and 7% Unknown. The mean vitamin D level was 22.5 (SD=11.9; range = <4 to 98), and 45% had level <20 ng/ml. Mean vitamin D levels (F=6.48, p=.002) and frequencies of vitamin D categories (p=.002, Chi square test) differed across the antiepileptic drug groups. Vitamin D deficiency was present in 54% of enzyme-inducing and 37% of non-enzyme-inducing antiepileptic drugs groups.

Vitamin D deficiency is common in patients with epilepsy on antiepileptic drugs. Monitoring of vitamin D should be considered as part of the routine management of patients with epilepsy.