The hypothalamic-pituitary-thyroid axis in patients with schizophrenia

Serum concentrations of thyroxine (T-4), triiodothyronine (T-3), reverse tr iiodothyronine (rT(3)) and thyrotropine (TSH) were measured in 31 acutely i ll in-patients with schizophrenia before and after four weeks of treatment with the phenothiazine derivative perazine. The serum levels of all the abo ve hormones were also determined in 19 schizophrenic patients in remission who were receiving no medication, 20 schizophrenic patients in remission ta king neuroleptic drugs, and 24 patients with residual-type schizophrenia. The serum levels of T-4 of acutely ill schizophrenic patients were elevated , while those of T-3, rT(3) and TSH were normal. Their T-4 levels showed a positive correlation with the severity of illness and the degree of clinica l response to neuroleptic treatment. There was a significant fall in serum concentrations of T-4 and rT(3) during four weeks of drug treatment and the decrease was significantly correlated to clinical response. No abnormaliti es in the serum concentrations of any of the hormones measured were found i n schizophrenic patients in remission or in residual-type schizophrenia. In conclusion, our results indicate that the elevated serum levels of T-4 m ay be specific for acutely ill schizophrenic patients and that neuroleptic medication may affect thyroid hormone metabolism, this interaction being in volved in the mechanism of action of these drugs. (C) 2000 Elsevier Science B.V. All rights reserved. JEL classification.