The effects of carbamazepine on the thyrotropin response to thyrotropin-releasing hormone.

A thyrotropin (thyroid-stimulating hormone; TSH) stimulation test with thyroid-releasing hormone (TRH) was performed on six patients with a DSM-III diagnosis of major depressive disorder, both before and during a trial of carbamazepine. Carbamazepine, an anticonvulsant effective in the treatment of affective illness, caused a reduction in the TSH response to TRH. This finding suggests that carbamazepine may decrease thyroid function primarily at the level of the pituitary in affectively ill patients.