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]
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 Type:||Refereed Article|
|Research Division:||Biomedical and Clinical Sciences|
|Research Group:||Clinical sciences|
|Objective Group:||Clinical health|
|Objective Field:||Clinical health not elsewhere classified|
|UTAS Author:||Burgess, JR (Professor John Burgess)|
|Web of Science® Times Cited:||9|
|Deposited By:||Menzies Institute for Medical Research|
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