Using the protirelin test to distinguish mania from schizophrenia.

To explore the possible utility of the protirelin test in differentiating manic and schizophrenic patients, we gave a test dose of protirelin to 30 consecutive euthyroid inpatients who met Research Diagnostic Criteria for mania, 30 who met criteria for schizophrenia, undifferentiated subtype, and 20 normal volunteer controls. The mean maximal thyroid-stimulating hormone (TSH) response (delta TSH) to protirelin in the manic patients was lower than in the schizophrenic patients and in the controls. This mean difference was not attributable to differences in age, sex, baseline thyroid functioning, cortisol levels, or medication, but there was a considerable overlap of values in the patient groups. However, with a delta TSH less than or equal to 7.0 I microunits/mL to identify manic patients in the overall group, the sensitivity of the protirelin test was 60% and the specificity was 84%.