THE HYPOTHALAMIC-PITUITARY-THYROID AXIS IN DEPRESSIVE PATIENTS AND HEALTHY-SUBJECTS IN RELATION TO THE HYPOTHALAMIC-PITUITARY-ADRENAL AXIS

Serum levels of thyroid stimulating hormone (TSH), triiodothyronine (T 3), free T3 index (fT3i), thyroxine (T4), and free T4 index (fT4i) wer e measured before and after administration of 1 mg of dexamethasone in 54 depressive patients and 54 matched healthy subjects. A followup st udy at a mean of 2 years was performed in 28 patients in remission. Ba sal TSH levels were lower and fT4i levels were higher in major depress ive patients compared with healthy subjects. After dexamethasone admin istration, there was no significant change in any of the hormones in a subgroup of 46 major depressive patients in contrast to matched healt hy subjects, who showed a significant decrease in the levels of TSH, T 3, and fT3i. The magnitude of the TSH response to dexamethasone in the major depressive patients was related to the level of nocturnal urina ry cortisol excretion and pathological dexamethasone suppression test results. The level of TSH in depressive patients during remission did not return to levels similar to those found in the healthy subjects.