Thyroid failure and protirelin (thyrotropin-releasing hormone) test abnormalities in depressed outpatients.

Forty-four consecutive outpatients referred to a psychiatric hospital for evaluation of depression and anergia were assessed by means of the protirelin (thyrotropin-releasing hormone) test. Nineteen patients (43%) had a blunted thyrotropin (TSH) response to protirelin, while six patients (13.5%) had augmented TSH responses indicating some degree of hypothyroidism. One patient had a low thyroxine level, while three patients had elevated basal TSH levels. Five of the six patients with augmented TSH responses were found to have antithyroid antibodies. These results suggest that a majority of depressed outpatients have abnormalities on the protirelin test and that the TSH response to protirelin is useful in both confirming a diagnosis of major depression and assessing thyroid status.