Cortisol, 11-deoxycortisol, and ACTH concentrations after dexamethasone in depressed patients and healthy volunteers.

The 1 mg dexamethasone suppression test was used to assess pituitary-adrenal activity in 23 depressed patients and 8 healthy volunteers. At 1600h, after administration of the test dose of dexamethasone at 2300h, levels of cortisol, 11-deoxycortisol, and corticotropin were determined following a chromatographic extraction step applying highly specific radioimmunoassay techniques. Cortisol nonsuppressors had significantly increased adrenocorticotropic hormone (ACTH) values and cortisol/11-deoxycortisol ratios. The cortisol/11-deoxycortisol ratio was regarded as a measure of biologically active ACTH. The present results, which indicate a concordance of corticotropin and corticosteroid response, suggest that the parent abnormality of dexamethasone-resistant cortisol concentrations is elevation of biologically active corticotropin.