The low dose dexamethasone suppression test: Effect of time of administration and dose

Abstract

The dexamethasone suppression test (DST) is used to determine the sensitivity of the hypothalamic-pituitary-adrenal axis (HPA-axis) to negative feedback. Dexamethasone is usually administered at 23:00 h or at midnight but this is often not convenient. The aim of this study was to determine whether the administration of dexamethasone at 21:00 h as compared to 23:00 h would alter the degree to which 08:00 h plasma cortisol was suppressed the following morning. Three healthy males (mean+/-SE: 32+/-7 yr) and 3 healthy females (mean+/-SE: 35+/-7 yr) took part in the study. Each subject was orally administered 1 of 3 doses of dexamethasone (0.25 mg, 0.5 mg, or 1.0 mg) on 3 separate occasions in random order at least a week apart. Each dose of dexamethasone was taken at either 21:00 h or 23:00 h so that each subject underwent 6 tests. The differences in cortisol suppression between times and doses of dexamethasone were assessed using Analysis of Variance. Plasma cortisol was suppressed less in response to 0.25 mg dexamethasone at both 21:00 h and 23:00 h as compared with doses of dexamethasone of 0.5 mg or 1.0 mg (p=0.004). Suppression of plasma cortisol in response to each dose of dexamethasone was similar regardless of the timing of dexamethasone administration (p=0.5). We conclude that in healthy subjects 0.25 mg dexamethasone suppresses plasma cortisol less than either 0.5 mg or 1.0 mg and that 0.5 mg dexamethasone suppresses plasma cortisol to a similar extent as 1.0 mg dexamethasone. Moreover, changing the administration time of dexamethasone from 23:00 h to 21:00 h does not effect the degree to which cortisol is suppressed in healthy subjects.

Association between HOMA-IR and Frailty among U.S. Middle-aged and Elderly Population

“…Frailty is a dynamic state affecting an individual who experiences accelerated decline in several domains of homeostatic mechanisms (physical, psychological, and social) 12 . One previous study showed the predictive value of HOMA-IR on habitual gait speed, one of the domains of frailty 13 .…”

The role of glucocorticoids in naturally fasting grey seal (Halichoerus grypus) pups: dexamethasone stimulates mass loss and protein utilisation, but not departure from the colony

“…This occurred in the face of higher circulating cortisol levels prior to dexamethasone treatment compared with the same time on the previous day, which was likely a result of repeated handling (Sapolsky et al, 2000;Bennett et al, 2012). In bottlenose dolphins, humans and horses, a similar or slightly higher mass-specific dose of dexamethasone causes suppression of circulating cortisol to 0-30% of initial levels within 24h and has observable effects on food-seeking behaviour (Barton et al, 2002;Froin et al, 1998;Reidarson and McBain, 1999). The rapid, dramatic and sustained impact of the dose of dexamethasone used here indicates that it mimicked the negative feedback effect of high levels of endogenous cortisol over a period of 1-2days.…”

Association of pre-chemotherapy peripheral blood pro-inflammatory and coagulation factors with reduced relative dose intensity in women with breast cancer

“…Among these, some of the most widely studied biomarkers of aging are inflammatory mediators and coagulation factors, such as IL-6, TNF-α, CRP and D-dimer. Inflammatory and coagulation markers are easily measured, increase with age, and are associated with functional decline and increased mortality in community-dwelling older adults [8, 12, 13, 25, 37–41]. …”