Cortisol Test
Reviewed
A cortisol test measures the level of cortisol in your blood, urine, or saliva. Cortisol is a hormone made by the adrenal glands that helps your body respond to stress, reduce inflammation, control blood sugar and metabolism, and regulate blood pressure. The test is used to help diagnose or rule out conditions that cause too much or too little cortisol, such as Cushing's syndrome (high cortisol), Addison disease (low cortisol), or secondary adrenal insufficiency (low cortisol). It may also be used to monitor treatment for these conditions.
Preparation and collection
Preparation depends on the type of test. Follow your provider's instructions. Stress and exercise can raise cortisol levels, so you may need to rest before your test. For a blood test, you will need two appointments at different times on the same day. Before a saliva test, you may need to stop using certain medicines. Tell your provider about all medicines you use, including skin creams, but do not stop any medicines without talking with your provider.
Understanding this test
Use the reference interval and units printed by the laboratory that performed the test. A result outside that interval is not a diagnosis by itself, and a result inside it does not rule out every condition. Your symptoms, history, medicines, timing, and related tests can change what the result means.
- A cortisol test alone cannot diagnose the cause of abnormal cortisol levels; additional testing is needed.
- Cortisol levels can be affected by stress, pregnancy, exercise, hot and cold temperatures, certain medicines (e.g., birth control pills), and steroid medicine use or sudden discontinuation.
- High cortisol levels may come and go in some people (pseudo-Cushing's syndrome), which may be caused by depression, anxiety, alcohol use disorder, poorly controlled diabetes, obesity, and other health problems.
What to do next
If your cortisol level is not normal, you will usually have more tests to find out what is causing the problem. To learn what your test results mean, talk with your provider.