Abstracts

Rationale: Osteoporosis and related fractures are very common in patients with epilepsy owing to limitations in sun exposure and physical activity as well as treatment with anticonvulsant medications. Besides hepatic enzyme induction, direct effects of AED on bone cells, resistance to parathyroid hormone, impaired calcium absorption and inhibition of calcitonin secretion may play a crucial role in the occurrence of osteoporosis. These risks prompted evaluation of 25-hydroxy-vitamin D levels in patients followed at our seizure clinic.Methods: 25-hydroxy-vitamin D level was measured in 201 ambulatory epileptic patients (107 males) who presented to our center over the last 3 years. Correlation was made with the AED they had been on before or during the period of the measurement. Vitamin D deficiency was defined as levels <20 mg/ml. Subjects were classified by gender and anticonvulsants were divided into enzyme inducing AED (EIAED: phenytoin, phenobarbital, carbamazepine, oxcarbazepine, felbamate and primidone) and non-enzyme inducing AED (NEIAED: valproic acid, lamotrigine, clonazepam, gabapentin, pregabalin, topiramate and ethosuximide). Subgroup analysis was performed to further assess the prevalence of vitamin D deficiency among the EIAED and the NEIAED monotherapy group. Enrollment is ongoing.Results: The mean age was 39.5 years old (range 7-85) with a mean vitamin D level of 24.8 ng/ml, with a mean of 23 for the male population and 26.4 for the female. 45.2% (n=91) of the total group of patients were vitamin deficient (44.8% of the male patients and 45.7% of the female patients studied). The average number of AED prescribed before or during the measurements were 2.2 per patient with an equal representation in the amount of EIAED versus NEIAED. Subgroup analysis of patients only on lifetime monotherapy with EIAED (n=53) yielded 45.2% (n=24) prevalence of vitamin D deficiency in this population, while enrollment and similar analysis for the NEIAED monotherapy group is pending. Conclusions: Vitamin D deficiency, a major risk factor for osteoporosis, remains an under recognized and under diagnosed disease. Our data suggests that it is highly prevalent in an ambulatory population of patients with epilepsy where nutritional, sun exposure and physical activity restrictions do not apply as strongly as in institutionalized patient. Nearly half the population evaluated demonstrated insufficient 25 hydroxy vitamin D levels (< 20 ng/ml) indicating that, irrespective of causality, vitamin D deficiency is prevalent and should be assessed more aggressively. The deficiency is also very frequent in the male patients. EIAED appear to play a major role in vitamin D deficiency. Further analysis is required to demonstrate if vitamin D deficiency from EIAED may result in permanently altered 25-hydroxy-vitamin D levels, despite change to NEIAED and treatment with vitamin D.