TRH test abnormalities in psychiatric disorders

Blunted responses to thyrotropin-releasing hormone (TRH) stimulation have been found consistently in depressed patients, and have been reported in other affective disorders as well. In a smaller number of schizophrenic subjects, TRH tests have generally been normal. Thus, it has been suggested that this test may have diagnostic utility in distinguishing schizophrenia from affective disorders. In the present study the TRH test was performed upon a sample of 51 subjects that included 17 schizophrenics in order to further study the diagnostic or symptom specificity of this endocrine test. Abnormal TRH tests were present in both schizophrenic and affectively disturbed patients. There were no correlations with ratings of depression or other aspects of psychopathology. Factors which may have previously obscured abnormal TRH tests in schizophrenia are discussed.