Cortisol Test

Why this test may be ordered

• Symptoms of Cushing's syndrome (too much cortisol): weight gain, thin arms and legs, round face, increased fat around the base of the neck or between the shoulders, easy bruising, wide purple streaks on the stomach, breasts, hips, and under the arms, muscle weakness.
• Symptoms of Addison disease and adrenal insufficiency (too little cortisol): long-lasting fatigue, muscle weakness, loss of appetite, weight loss, abdominal pain.
• To monitor treatment for conditions affecting cortisol levels.

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.

Blood draw from a vein; 24-hour urine collection; saliva sample collected with a swab or by spitting into a tube.

Blood test: There is very little risk. You may have slight pain or bruising at the spot where the needle was put in, but most symptoms go away quickly. Urine or saliva test: According to MedlinePlus, there are no known risks to a urine or saliva test.

Understanding results

A cortisol test measures the level of cortisol in your blood, urine, or saliva. Cortisol levels normally vary throughout the day, with highest levels in the morning and lowest around 4 p.m. Abnormal levels may indicate a condition affecting your adrenal glands or pituitary gland, but the test alone cannot diagnose the cause.

• High cortisol level: High levels of cortisol may be a sign of Cushing's syndrome, which can be caused by taking high doses of certain steroid medicines for a long time, tumors that make extra ACTH (in the pituitary gland or other parts of the body), or tumors in the adrenal glands that make extra cortisol. Limitation: A cortisol test alone cannot diagnose the cause of abnormal cortisol levels. Next step: If your cortisol level is not normal, you will usually have more tests to find out what is causing the problem.
• Low cortisol level: Low levels of cortisol may mean you have Addison disease or secondary adrenal insufficiency. Common causes of Addison disease include autoimmune diseases, certain infections (e.g., tuberculosis, HIV). Common causes of secondary adrenal insufficiency include autoimmune diseases, problems with the pituitary gland, traumatic brain injury, or surgical removal of the pituitary gland. Limitation: A cortisol test alone cannot diagnose the cause of abnormal cortisol levels. Next step: If your cortisol level is not normal, you will usually have more tests to find out what is causing the problem.

• 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.

• What do my cortisol test results mean?
• Do I need additional tests to confirm a diagnosis?
• Could my medicines or other factors affect my cortisol levels?

Evidence source

U.S. National Library of Medicine: Cortisol Test