[A study of thyroid function in patients with psychoaffective disease (author's transl)]

The purpose of the present study was to investigate dysfunctions in thyroid gland secretion and regulation among patients with manic-depressive psychosis. Plasma levels of thyroxine (T4), triiodothyronine (T3) and thyroid stimulating hormone (TSH) were measured by radioimmune assays, and TSH responsiveness (delta TSH) to synthetic TSH-releasing hormone (TRH) 250 microgram IV was determined in 20 untreated patients, 19 patients under neuroleptics and 19 patients under antidepressants. Untreated patients were compared with 15 age - and sex-matched controls. They were found to have significantly lower plasma T3 levels than controls (121.0 +/- 6.0 ng/dl as against 144.5 +/- 3.3 ng/dl; p less than 0.01) and blunted TSH response to TRH (delta TSH 4.1 +/- 0.6 instead of 12.6 +/- 2.1). Other thyroid function parameters were unchanged. Under neuroleptic treatment T3 levels tended to increase and delta TSH returned to normal. Manic-depressive psychosis is characterized by hypothalamic-pituitary dysfunction. Thyroid secretion is normal, and the decrease in T3 is probably due to impaired peripheral T4 to T3 conversion.