Table of Contents
- Overview
- Results
- Risks
- Prevention
The health care provider may advise you to stop taking drugs that may affect the test. Drugs that can affect test results include:
- Barbiturates
- Corticosteroids
- Estrogens
- Oral birth control (contraceptives)
- Phenytoin
- Spironolactone
- Tetracyclines
How the test will feel
When the needle is inserted to draw blood, some people feel moderate pain, while others feel only a prick or stinging sensation. Afterward, there may be some throbbing.
Why the test is performed
This test is performed when the health care provider suspects that your body is producing too much cortisol. It is done to help diagnose Cushing syndrome and identify the cause.
The low-dose test can help tell whether your body is producing too much cortisol. The high-dose test can help determine whether the problem is in the pituitary gland (
The level of cortisol in the blood normally regulates the release of ACTH from the pituitary gland. As blood cortisol levels increase, ACTH release decreases. As cortisol levels decrease, ACTH increases.
Dexamethasone is a human-made (synthetic) steroid that is similar to cortisol. It reduces ACTH release in normal people. Therefore, taking dexamethasone should reduce ACTH levels and lead to decreased cortisol levels.
If your pituitary gland produces too much ACTH, you will have an abnormal response to the low-dose test, but a normal response to the high-dose test.
Review Date: 11/23/2009
Reviewed By: Ari S. Eckman, MD, Division of Endocrinology and Metabolism, Johns
Hopkins School of Medicine, Baltimore, MD. Review provided by
VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA,
Medical Director, A.D.A.M., Inc.
A.D.A.M., Inc. is accredited by URAC, also known as the American Accreditation HealthCare Commission (www.urac.org)
