Dexamethasone suppression test

Dexamethasone Suppression Test

The Dexamethasone suppression test is a type of diagnostic test utilized to detect cortisol levels as a measure of Cushing's Syndrome or Hypercortisolism. It also helps to distinguish between other adrenal gland illnesses.


No special preparation is required for this test. Patients are advised to communicate to the physician about their medical history, results of previous tests, current medications and other supplements they are taking. The physician may ask the patient to discontinue or reduce the dosage of medication being taken in order to get accurate results from the Dexamethasone suppression test.


The test involves taking two doses of Dexamethasone, an artificial corticosteroid. The first dose is taken in the morning and the second dose is taken at 11 p.m. After these two doses, the patient will have three blood tests at 9 a.m., 4 p.m. and 11 p.m. on the following day. The results of these tests will indicate the presence or absence of cortisol.


There are two types of the Dexamethasone suppression test:

  • Low-dose Dexamethasone suppression test
  • High-dose Dexamethasone suppression test


The Dexamethasone suppression test is considered to be safe, and rarely causes any side effects. However, a very small percentage of people may experience headaches, dizziness or nausea during or after the test.

Why is it done

This test is usually recommended to people who have experienced a rapid weight gain, high blood pressure, discoloration in the skin and other signs or symptoms of Cushing's Syndrome. It is also used to help differentiate the condition from other adrenal gland disorders.

When is it done

The Dexamethasone Suppression test is usually done when an individual is suspected to have symptoms of Cushing's syndrome, such as rapid weight gain, thinning skin, mood changes, purple or pink stripes on the abdomen and other associated signs.