Dexamethasone Suppression Test
Introduction The dexamethasone suppression test (DST) is a screening test to rule out Cushing syndrome . Dexamethasone suppression test is used in combination with other tests (midnight plasma cortisol, late-night salivary cortisol, and/or 24-hour urinary free cortisol) to confirm the diagnosis. A suppression test, in general, involves giving the patient a substance that would normally cause the inhibition of the release of the hormone. However, due to the excessive amounts of hormone or hyperfunction of the endocrine organ, a patient with the disease state would fail to have the hormone levels suppressed. Regimen It may be administered as a Low-dose test Screening for Cushing syndrome Overnight test: 1 mg PO between 11 PM and 12 AM; cortisol level tested between 8 AM and 9 AM on following morning. Standard 2-day test: 0.5 mg PO q6hr (9 AM, 3 PM, 9 PM, 3 AM) for 2 days; cortisol level tested 6 hours after final dose (9 AM). High-dose test Confirmed Cushing syndrome in which further wo...