Thyroid-stimulating hormone response to thyrotropin-releasing hormone in unipolar depression before and after clinical improvement.

Fourteen patients with unipolar depression who had a blunted thyroid-stimulating hormone (TSH) response to infusion of 500 micrograms of thyrotropin-releasing hormone (TRH) and who showed marked clinical improvement after pharmacotherapy and/or electroconvulsive therapy had the TRH test repeated after improvement. The mean (+/- SD) maximal TSH response to TRH (delta TSH) increased significantly from 4.0 +/- 1.9 to 9.1 3.5 micro IU/ml. The number of patients with delta TSH less than 7.0 micro IU/ml increased significantly from 0 to 9 of 14 after improvement. Eleven of the patients were followed for 5 to 19 months, and none showed clear relapse. The results suggest that the blunted TSH response to TRH has features of both a state marker for active unipolar depression and a trait marker for vulnerability to this illness, and support the suggestion that the TRH test may be useful in diagnosis and treatment planning.