The TRH test in the diagnosis of major and minor depression

(1) The effect of TRH on TSH and GH release was studied in 144 consecutive psychiatric admissions. The magnitude of the TSH response to TRH differentiated unipolar from clinically similar and dissimilar groups. (2) Of 41 patients with unipolar depression, 31 had a ΔTSH of ≤7 μI.U./ml while only 1 of 12 bipolar and 0 of 10 minor depressive patients had a ΔTSH of ≤7 μI.U./ml. (3) A ΔTSH of ≤7 μI.U./ml is a frequent finding in unipolar depression and infrequently associated with other psychiatric diagnoses. (4) The data reported support the hypothesis that patients with a ΔTSH of ≤7 are unipolar depressives. (5) Six of 12 bipolar and 17 of 41 unipolar depressives had a GH response to TRH while none of the patients with a minor depression had a significant GH response. These data suggest that major and minor depressions can be separated on the basis of the TRH-induced GH response test. (6) The magnitude of the TRH-induced TSH response and the presence of a pathological GH response may be extremely useful in differentiating manics from schizophrenics and other similarly appearing patient groups. (7) The TRH test is useful in clinical differential diagnosis of dysphoric states and as a confirmatory laboratory test for major depressive disease and unipolar depression.