Background: Due to the high prevalence of epilepsy, antiepileptic drugs are widely prescribed for the epileptic patients. One of the major side effects of these drugs is their negative effect on thyroid function. The aim of this study was to examine the effects of sodium valproate and phenobarbital on thyroid function in children.

Materials and Methods: This case-control study was conducted on children with the first epileptic experience or those epileptic children who had not received any medication. The participants were allocated into three groups: the sodium valproate (31 cases), phenobarbital (22 cases), and control (60 cases) groups. Serum level of TSH and T4 before the treatment and 1 and 3 months later were measured and analyzed.

Results: Mean age of the children (60 male and 53 female cases) was 3.83±2.01 years. No difference was found among the three groups regarding the age and sex. In the valproate group, the level of TSH was increased only within 3 months after the treatment, while no change was detected in T4. There was no detected change for the thyroid hormones in the phenobarbital group as well.

Conclusion: Phenobarbital had no effect on thyroid tests, while sodium valproate appeared to increase the TSH in the epileptic patients. Therefore, further studies are recommended in this regard with the consideration of the relevant clinical signs.