The relationships of neuroendocrine tests in endogenous depression.

Amphetamine induced growth hormone (GH) response (Study 1) and TRH induced TSH response (Study 2) were assessed in patients with endogenous depression (n = 20 and n = 22, respectively), who underwent a dexamethasone suppression test (DST) on the following day. The GH response to the amphetamine was significantly lower in the group of depressed patients than in the healthy controls (n = 13). There was no difference between the DST nonsuppressors (n = 12) and suppressors (n = 8) in the GH peak values. This data strongly suggests that the two tests are independent from each other. There was no significant relationship between the DST and TRH-TSH results. Patients with blunted TSH response to TRH have had significantly higher cerebrospinal fluid 5-HIAA levels.