Thyrotropin-releasing hormone (TRH) stimulation tests were performed in 19 patients with endogenous depression before treatment and when they had apparently recovered following antidepressive treatment. An increase in the maximal serum thyrotropin (TSH) response to TRH of more than 2.0 muU/ml was found in all of ten patients who did not relapse, while such an increase was found in only one of nine patients who did relapse within 6 months. I. e., a correct prognosis was possible in 94.7% (95% confidence limits 74.0 - 99.9%). Through significant changes were found in serum thyroxin (T4), free T4 index, serum triiodothyronine (T3) and free T3 index, these findings were of no prognostic value.

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