Free-thyroxine index in schizophrenic patients before and after neuroleptic treatment.

The mean values of serum thyroxine (T4), in vitro radioactive triiodothyronine uptake and free-thyroxine index (FTI) in 41 drug-free schizophrenic patients did not differ significantly from those of euthyroid controls. Following 6 weeks' treatment of 24 schizophrenics with chlorpromazine, trifluoperazine or clozapine, a significant decrease in serum T4 and FTI was noted after chlorpromazine and clozapine, whereas after trifluoperazine only serum T4 decreased, but not FTI. The questions arising from these findings are discussed and the need for a future investigation of serum triiodothyronine and serum TSH in schizophrenic patients before and after neuroleptic treatment is stressed.