Aim to estimate serum vitamin D level and some biochemical markers of bone turnover in Egyptian children with epilepsy on antiepileptic drugs.

Methods Case control cross sectional study was conducted on thirty children with epilepsy (19 males, and 11 females) on anticonvulsant therapy, divided into two subgroups according to mode of therapy; 15 under polytherapy (group I) 15 under monotherapy (group II). Twenty apparently healthy children were recruited as control group.

Results Epileptic patients on polytherapy had highly significant low serum 25-hydroxy vitamin D level compared to those on monotherapy (p < 0.001) with highly significant differences between patients versus controls (p < 0.001). Over two third of patients 80% (24 /30) had low serum 25-OHD levels; 26.67% (8/30) had 25-hydroxyl vitamin D levels less than 20 ng/mL, and 53.33% (16/30) patients had 25-hydroxy vitamin D levels between 21 and less than 32 ng/ml. Differences between the cutoff categories were highly statistically significant for patients versus controls (p < 0.001), and among the polytherapy versus monotherapy subgroups (p < 0.001). Patients on polytherapy showed highly significant lower level of 25-hydroxyvitamin D compared to those on valoproate alone, or carbamazepine alone (F=32.345, p < 0.001) by ANOVA.

Conclusion Results revealed high risk of vitamin D deficiency in epileptic children on antiepileptic drugs especially those under long term polytherapy. Alterations of biochemical markers of bone formation suggest an accelerated skeletal turnover. Routine monitoring of serum 25- hydroxy vitamin D is recommended.