Behavioral and Endocrine Responses of Schizophrenic Patients to TRH (Protirelin)

Abstract

• 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 symtpoms. 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.