APA Dictionary of Psychology

a test of the ability of dexamethasone, a synthetic analogue of cortisol, to inhibit the secretion of corticotropin and hence suppress levels of cortisol in the blood. In the test, dexamethasone is administered, and after a waiting period, cortisol levels are assessed. In normal individuals, cortisol levels will be suppressed by dexamethasone. If cortisol is still elevated, the individual is categorized as a nonsuppressor. The test is a common research tool, but its primary clinical use is to aid in the diagnosis of Cushing’s syndrome.