Overnight Dexamethasone Suppression Test
Also written as: ODST — Overnight Dexamethasone Suppression Test
A screening test for Cushing's syndrome using dexamethasone to suppress normal cortisol production.
Full Definition
The overnight dexamethasone suppression test (ODST) is a screening procedure for Cushing's syndrome in which 1 mg of dexamethasone is administered at 11 PM, followed by measurement of serum cortisol at 8 AM the next morning. In normal individuals, dexamethasone suppresses ACTH release, resulting in cortisol levels below 1.8 μg/dL (50 nmol/L). Failure to suppress cortisol suggests autonomous cortisol production, warranting further evaluation for Cushing's syndrome. This test has high sensitivity but moderate specificity for detecting hypercortisolism.
Usage
Usage note: Specify timing (overnight) to distinguish from other dexamethasone suppression protocols.
In Context
- "The overnight dexamethasone suppression test showed inadequate cortisol suppression at 8.5 μg/dL." — Endocrinology screening report
- "ODST is the preferred initial screening test for suspected Cushing's syndrome." — Clinical practice guideline