Thyroid functions in children under long-term administration of antiepileptic drugs

Objective In this study we investigated whether long-term administration of antiepileptic drugs effect thyroid functions. Methods Serum free thyroxine (FT4), serum free triiodothyronin (FT3) and serum thyroid stimulating hormone (TSH) concentrations were measured in 93 epileptic patients receiving phenobarbital (30 cases) or phenytoin (9 cases) or carbamazepine (23 cases) or valproate (22 cases) or clonazepam (9 cases) who were admitted to Trakya University School of Medicine, Department of Pediatrics, between July 1992 and May 1994. Results We found a significant reduction in FT4 levels receiving phenobarbital or phenytoin or carbamazepine or clonazepam compared to control group. FT3 and TSH levels were normal. However, in the valproat group there was not any significant difference in the levels of thyroid hormones between study and control groups. All patients were in euthyroid state, there were no clinical findings of hypothyroidism. Conclusion These data suggest that phenobarbital, phenytoin, carbamazepine and clonazepam decrease serum FT4 , hovever while valproat does not.