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The 4-mg intravenous dexamethasone suppression test in the diagnosis of Cushing's syndrome

Citation

Jung, C and Alford, FP and Topliss, DJ and Burgess, JR and Long, F and Gome, JJ and Stockigt, JR and Inder, WJ, The 4-mg intravenous dexamethasone suppression test in the diagnosis of Cushing's syndrome, Clinical Endocrinology, 73, (1) pp. 78-84. ISSN 0300-0664 (2010) [Refereed Article]

DOI: doi:10.1111/j.1365-2265.2009.03756.x

Abstract

OBJECTIVE: Optimal diagnostic criteria for the 4-mg intravenous dexamethasone suppression test (IVDST) in patients with Cushing's syndrome (CS), compared with normal subjects, have not been established. We evaluated the performance of the 4-mg IVDST for differentiating CS from normal subjects and to define the responses in CS of various aetiologies.

DESIGN, SUBJECTS, MEASUREMENTS: Thirty-two control subjects [normal and overweight/obese participants with or without type 2 diabetes) were prospectively studied, and data from 66 patients with Cushing's disease (CD), three with ectopic ACTH syndrome (EAS), 14 with adrenal Cushing's (AC)] and 15 with low probability of CS (LPC) from three tertiary hospitals were retrospectively evaluated. Dexamethasone was infused at 1 mg/h for 4 h. Plasma cortisol and ACTH were measured at -60 min (baseline), -5 min, +3 h, +4 h, +5 h and at +23 and +23.5 h on Day 2.

RESULTS: Control subjects (including those with type 2 diabetes) exhibited a marked suppression of cortisol which was maintained until Day 2. Two of 15 patients with LPC had Day 2 cortisol results that overlapped with CS. Patients with CD demonstrated partial suppression, with rebound hypercortisolism on Day 2. Patients with AC and EAS did not suppress cortisol levels. Day 2 cortisol level of >130 nmol/l (or >20% of the baseline) diagnosed CS with 100% sensitivity and 96% specificity.

CONCLUSION: While the IVDST allowed complete discrimination between control subjects and CS, 13% of LPC overlapped with CS. Given the small number of EAS, no conclusion can be drawn regarding the utility of this test in the differential diagnosis of CS.

Item Details

Item Type:Refereed Article
Research Division:Medical and Health Sciences
Research Group:Clinical Sciences
Research Field:Endocrinology
Objective Division:Health
Objective Group:Clinical Health (Organs, Diseases and Abnormal Conditions)
Objective Field:Endocrine Organs and Diseases (excl. Diabetes)
Author:Burgess, JR (Professor John Burgess)
ID Code:94855
Year Published:2010
Web of Science® Times Cited:6
Deposited By:Menzies Institute for Medical Research
Deposited On:2014-09-18
Last Modified:2014-11-24
Downloads:0

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