Cortisol secretion and dexamethasone response in depression

Abstract

Dexamethasone [2 mg] was administered at 2300 h to 37 unmedicated hospitalized endogenously depressed patients and their plasma cortisol response was assessed at 1600 and 2300 h the next day. In addition, on nondexamethasone days 26 of these patients had mean 24 h plasma cortisol concentration determinations from samples taken at 30 min intervals and 32 had plasma determinations from a single sample taken at 1600 and 2300 h. Mean 24 h plasma cortisol concentration was elevated in 50%; only 7 of the 26 were dexamethasone resistant and 6 of these 7 were hypersecretors. Dexamethasone resistance may reflect the abnormality of cortisol hypersecretion in depression. The 2 mg dexamethasone suppression test is apparently a highly specific but not very sensitive indicator of hypersecretion.