Published in Epilepsy Research, a team of US-based researchers investigated vitamin D levels in patients with epilepsy and looked at the impact antiepileptic drugs (AED) had.
Findings showed 45% of patients with epilepsy on AED treatment were vitamin D deficient (less than 20 ng/ml) – higher than deficiency levels in the general US population (32%). The mean vitamin D level was 22.5 ng/ml.
The researchers found that vitamin deficiency levels differed according to the type of AEDs the patients were on. More than half (54%) of those on enzyme-inducing AEDs were vitamin D deficient, compared to 37% on non-enzyme inducing AEDs.
“…The high frequency of vitamin D deficiency in the epilepsy population highlights the importance of screening and appropriate treatment in patients with epilepsy,” the researchers wrote.
Presently, there were no guidelines for assessment of vitamin D and bone health in patients with epilepsy other than the Endocrine Society’s recommendation to screen vitamin D levels in patients on AEDs, they said.
Vitamin D levels in patients with epilepsy should be continuously monitored as part of routine management, the researchers said, and calcium supplementation should also be considered.
“Although additional research is needed to assess the utility of vitamin D and calcium supplementation, we feel that the intake of calcium and vitamin D should be optimized in all persons with epilepsy treated with AEDs given the higher risk of osteoporosis and fractures in this population,” they said.
Bone health when taking AEDs
The positive impact vitamin D had on bone health was the most important factor when considering supplementation among epileptics, the researchers said.
Osteoporosis was more common in epileptics and risks were often exacerbated with long duration AED treatment, they said. Epilepsy patients were also two to six times more likely to suffer fractures due to a number of factors, including seizures, impaired balance, inactivity, low bone mineral density and inadequate calcium intake, they said.
“Even though risk increases with duration of AED treatment, reduced bone mineral density can be seen in the first year of AED therapy.”
Beyond bone health, several studies had suggested vitamin D deficiency may contribute adversely to autoimmune disorders like multiple sclerosis, as well as cancer, chronic fatigue, depression and diabetes, the researchers wrote.
In addition, animal and human studies suggested vitamin D deficiency may worsen seizures, they said, although added that more research was needed to confirm these observations.
The observational study examined 596 epilepsy patients with a mean age of 41 years treated by two clinicians at the Emory University Epilepsy Center from 2008 to 2011. Just over half (56%) were women, 55% Caucasian, 34% Black, 2% Asian and 7% Unknown.
Vitamin D 25-OH levels were categorised as low (<20 ng/ml), borderline (20-29 ng/ml) or normal (≥30 ng/ml).
The researchers categorised antiepileptic drugs based on their enzyme inducing properties.
Source: Epilepsy Research
Published online ahead of print, doi: 10.1016/j.eplepsyres.2014.06.008
“Low vitamin D levels are common in patients with epilepsy”
Authors: DL. Teagarden, KJ. Meador and DW. Loring