The combined dexamethasone/corticotropin-releasing hormone stimulation test is more closely associated with features of diurnal activity of the hypothalamo-pituitary-adrenocortical system than the dexamethasone suppression test.

BACKGROUND

The dexamethasone suppression test (DST) is a widely used endocrine test in psychiatry, but was reported to not allow reliable inferences with regard to the basal activity of the hypothalamo-pituitary-adrenocortical (HPA) system. We compared the association of the standard DST and the combined dexamethasone/corticotropin-releasing hormone (DEX/CRH) challenge with parameters of diurnal cortisol profiles.

METHODS

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-matched healthy controls (mean age: 51.4 +/- 19.3 years).

RESULTS

A path analysis showed cortisol area under the curve (AUC) after CRH (= DEX/CRH status) to be dependent upon minimal 24-hour cortisol and evening frequency of pulsatile cortisol release. In contrast, postdexamethasone cortisol (= DST status) was related to 24-hour mean cortisol. Simple linear regressions supported an association of cortisol AUC with several parameters of the diurnal cortisol profiles, which was not true for the standard DST.

CONCLUSIONS

We conclude that the combined DEX/CRH challenge test is more closely associated with the activity of the HPA system than the standard DST in healthy and depressed subjects.