Overnight Dexamethasone Suppression Test

ACTH Suppression Test, Cortisol Suppression Test, Dexamethasone Suppression Test (DST), DST (Dexamethasone Suppression Test)

Results

The overnight dexamethasone suppression test involves taking a dose of a corticosteroid medication called dexamethasone to see how it affects the level of a hormone called cortisol in the blood. This test screens for Cushing's syndrome, a condition in which excess amounts of cortisol are being produced by the adrenal glands. Test results are usually available in 2 to 3 days.

Normal

Overnight dexamethasone suppression test

Normal:	Cortisol level is less than 5 mcg/dL or less than 150 nmol/L.

High values

High cortisol levels may be caused by:

• Cushing's syndrome.
• Other health problems, such as a heart attack or heart failure, fever, poor diet, an overactive thyroid gland (hyperthyroidism), depression, anorexia nervosa, uncontrolled diabetes, or alcoholism.
• Cancers that make ACTH, such as lung cancer.

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Author:	Sydney Youngerman-Cole, RN, BSN, RNC	Last Updated August 3, 2006
Medical Review:	Caroline S. Rhoads, MD - Internal Medicine David C.W. Lau, MD, PhD, FRCPC - Endocrinology & Metabolism
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