Potential risk factors for vitamin D levels in medium- and long-term use of antiepileptic drugs in childhood

Antiepileptic drugs (AED) have potential side effects through vitamin-D. Prevalence of vitamin D insufficiency and potential risk factors for the longitudinal changes of vitamin D levels compared to its baseline levels under AED treatment were investigated in this study. This retrospective study includes patients whose AED therapy were started in only autumn months, between 2000 and 2014. Detailed assessment of neurologic diagnosis and brain MRI findings, ambulatory status, types and durations of AED treatment, and baseline bone health blood tests (vitamin-D, alkaline phosphatase, calcium, and phosphate levels) were obtained on all patients. Vitamin-D deficiency was defined as 25(OH)D <20 ng/mL, while vitamin-D insufficiency was defined as 25(OH)D between 21 and 29 ng/mL. A total of 172 children (mean age 9.6 ± 4.3 years) were followed up 5.3 years in average (range 1–14.7). The mean baseline 25(OH)D level was decreased from 24.4 ± 11.6 to 19.6 ± 10.7 ng/mL at the last follow up. The mean change in the vitamin-D levels (ΔD-vitamin) was −4.8 ng/mL (p = 0.003). The rate of vitamin-D deficiency was 54% and insufficiency was 25%. Multivariate logistic regression analysis identified only long-term use of AEDs as a risk factor for the longitudinal decrease. Monotherapy with valproic acid (n = 45), carbamazepine (n = 20), levetiracetam (n = 10) and phenobarbital (n = 12) was compared with each other. There was no difference in terms of longitudinal changes in 25(OH)D levels. In the treatment of childhood epilepsy, 25(OH)D levels should be monitored, especially when long-term AED used, in order to prevent D-hypovitaminosis.