Behavioral and endocrine responses of schizophrenic patients to TRH (protirelin)

We studied the effects of intravenous protirelin (thyrotropin-releasing hormone) in 17 schizophrenic patients and 17 normal subjects. A total of 12 patients received protirelin, 0.5 mg, and, on another occasion, niacin, 2 mg, in a double-blind, crossover design. Both behavioral and endocrine data were collected. Five patients received protirelin in an open trial; only endocrine data were collected. Protirelin caused about a 50% prompt decrease in psychotic symptoms. Patients then tended slowly to experience a relapse. Side effects were about as infrequent after protirelin as after niacin. We assayed serum prolactin (PRL), growth hormone (GH), thyroid-stimulating hormone (TSH), L-triiodothyronine (T3) and thyroxine (T4). Free T4 (FT4) index was calculated. The values for PRL, GH, and TSH at baseline and after protirelin stimulation were normal. Patients showed lower T3 values at baseline, but a brisker T3 response to protirelin, than controls. Their FT4 indices were higher at baseline. Patients showed diminished T4 binding sites rather than increased total T4. The causes of these alterations in thyroid dynamics are unidentified.