[Stimulated secretion of TSH in patients with depression of mild nature]

Several studies have demonstrated that a consistent part of patients with severe depression shows anomalous responses of neuroendocrine axes. In the last years, altered TSH responsiveness to exogenous TRH have been reported also in patients with panic disorders. Because of these suggestions we studied stimulated TSH secretion in 24 untreated hospitalized patients (8 males and 16 females), aged from 21 to 76, in whom the psychiatric examination disclosed mild but inequivocal signs of persistent depression (score range on Rufin and Ferreri Iventory from 20 to 35). The TRH-test (200 mcg i.v.) was started between 9.00 and 9.30 a.m.. The same test was performed also in 14 sex- and age-matched volunteers defined without psychiatric disorders. As comparison parameter, delta-TSH (maximum increase during TRH stimulation) was accounted. All the patients had normal serum thyroid hormone levels. TSH responsiveness of patients with minor depressive disorders was not found statistically different when compared with normal control volunteers, but a reverse significant correlation was found between delta-TSH and percentage score of anxiety in group of patients (with blunted TSH response in 6 (25%) patients), that was not found in normal subjects. A significant correlation between delta-TSH and depression degree was not found. The present data, although preliminary, could indicate the existence of depressed subjects in whom blunted TSH response to TRH seems related to anxiety degree. Additional studies, particularly on the medullo-adrenal function, might clarify the nature of these alterations, that at state is unclear, although the mechanisms suggested also for alterations of pituitary hormone responses in major depression could be taken in account.