Vitamin D Deficiency Highly Prevalent Among Epilepsy Patients

Caroline Cassels

December 06, 2007

December 6, 2007 (Philadelphia) — New research shows almost half of all patients with epilepsy are vitamin D deficient and suggests men are equally, if not more frequently, affected.

 

Presented here at the American Epilepsy Society 61st Annual Meeting, the study showed 44.5% of epilepsy patients — 45.3% of men and 43.7% of women — were vitamin D deficient, putting these patients at potential increased risk for a wide variety of conditions, including osteoporosis, autoimmune disease, cancer, cardiovascular disease, and infectious disease, among others.

"These results point out that vitamin D deficiency is very prevalent in the seizure population and that men are equally or even more often affected than women and therefore should not be overlooked or neglected," principal investigator Ioannis Karakis, MD, from Boston University School of Medicine, in Massachusetts, told Medscape Neurology & Neurosurgery.

The study's coinvestigator was Georgia Montouris, MD, also from Boston University School of Medicine.

According to Dr. Karakis, it is well-known that vitamin D deficiency in the general population is very common. In fact, he said, research by Michael F. Hollick, MD, PhD, also from Boston University School of Medicine, who is widely considered 1 of the top vitamin D researchers in the world, found that among a healthy group of physicians and residents, about one-third were vitamin D deficient (Tangpricha V et al. Am J Med. 2002;112:659-662).

More Risk Factors

According to Dr. Karakis, the investigators suspected vitamin D deficiency would be even higher in epilepsy patients, in large part because antiepileptic medications can affect vitamin D metabolism and lead to deficiency.

However, he said, patients with epilepsy often have other indirect risk factors that can predispose them to vitamin D deficiency, many of which relate to lifestyle changes due to their disease that limit sun exposure and physical activity and consequently impair their bone-mineral density.

"Being less ambulatory affects bone-mineral density, and staying indoors limits exposure to sunlight, which is a very important factor in vitamin D synthesis," said Dr. Karakis.

For the study, investigators measured 25-hydroxy-vitamin D levels in 285 ambulatory patients with a seizure disorder — 150 men and 135 women — attending a single-center seizure clinic.

Overall they found 44.5% (127) subjects had vitamin D deficiency, which was defined as serum levels of less than 20 ng/mL. When subjects were divided by sex, the study showed 45.3% (68) of men and 43.7% (59) of women had hypovitaminosis D.

All vitamin D deficient patients, said Dr. Karakis, were treated with 1 capsule of 50,000 IU of vitamin D2 per week for 8 weeks, at which time levels were rechecked. "Patients who were compliant experienced improvement," he said.

Men Deserve Equal Time

Dr. Karakis said it was somewhat surprising that vitamin D deficiency was more prevalent in men and highlights the need for clinicians to aggressively assess in this group of patients.

A subgroup analysis examined whether there was any difference in vitamin D deficiency–prevalence rates associated with monotherapy with enzyme-inducing antiepileptic drugs (EIAEDs) vs monotherapy with non–enzyme-inducing antiepileptics (NEIAEDs).

Practically speaking, said Dr. Karakis, NEIAEDs comprise the newer antiseizure medications, with the exception of valproate, an older AED that does not induce the hepatic cytochrome P450 system. Among the enzyme inducers, most are older agents, excluding oxcarbazepine, which is a partial enzyme inducer.

However, he said, with a prevalence rate of 46.2% and 34.2% for EIAEDs and NEIAEDs respectively, the difference was not very striking.

"The first indications from this study show that although the impact of non–enzyme-inducing antiepileptic medications on vitamin D levels is not as great [as EIAEDs], they still have an impact on bone health," said Dr. Karakis.

American Epilepsy Society 61st Annual Meeting: Abstract 3.337. November 30-December 4, 2007.

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