Effects of 12-month Antiepileptic Drug Use on Thyroid Functions in Children: A Retrospective Observational Study

Aim:The purpose of this study was to examine the effects of antiepileptics on thyroid function tests and to compare these effects among different antiepileptics.Materials and Methods:Two hundred and twenty patients (102 female and 118 male) aged 1-17 years indicated for antiepileptic drug (AED) therapy for epilepsy were enrolled in this study which was performed in a child neurology clinic between January 2014 and January 2018. Those patients using a single AED and with complete seizure control were included. In this study period, according to the local protocol, we measured free thyroxine (fT4) and thyroid-stimulating hormone (TSH) levels at the beginning of treatment and at the 12th month of AED therapy.Results:The mean age of the patients was 10.2±4.4 years. TSH elevation was observed in only eight patients. These eight patients’ thyroid autoantibodies were negative and their thyroid ultrasonography were normal. Subclinical hypothyroidism (TSH: 5-10, fT4 normal) was present in three of these eight patients, and they were therefore not started on medication. The other five were started on L-thyroxine. Four of these were using valproic acid and one was using carbamazepine. We found no significant difference between TSH and fT4 levels measured before the start and at the 12th month of drug therapy, nor among the different AEDs used.Conclusion:AEDs have no marked effects on thyroid function, and may therefore be safely used from that perspective