THE COMBINED DEXAMETHASONE CORTICOTROPIN-RELEASING HORMONE STIMULATION TEST IS MORE CLOSELY ASSOCIATED WITH FEATURES OF DIURNAL ACTIVITY OFTHE HYPOTHALAMO-PITUITARY-ADRENOCORTICAL SYSTEM THAN THE DEXAMETHASONE SUPPRESSION TEST/

Background: The dexamethasone suppression test (DST) is a widely used Endocrine rest in psychiatry, bur was reported to not allow reliable i nferences with regard to the basal activity of the hypothalamo-pituita ry-adrenocortical (HPA) system. We compared the association of the sta ndard DST and the combined dexamethasome/corticotropin-releasing hormo ne (DEX/CRH) challenge with parameters of diurnal cortisol profiles. M ethods: We performed a DEX/CRH challenge and 24-hour-cortisol profiles in 25 depressed patients (mean age: 47.4 +/- 16.0 years) and 33 age-m atched healthy controls (mean age: 51.4 +/- 19.3 years). Results: A pa th analysis showed cortisol area under the curve (AUC) after CRH (= DE X/CRH status) to be dependant upon minimal 24-hour cortisol and evenin g frequency of pulsatile cortisol release, In contrast, post-dexametha sone cortisol (= DST status) I-vas related to 24-hour mean cortisol, S imple linear regressions supported an association of cortisol AUC with several parameters of the diurnal cortisol profiles, which was not tr ue far the standard DST. Conclusions: We conclude that the combined DE X/CRH challenge test is more closely associated with the activity of t he HPA system than the standard DST in health; and depressed subjects. (C) 1998 Society of Biological Psychiatry.