Cortisol Test

What is a cortisol test?

A cortisol test measures the level of cortisol in your blood, urine (pee), or saliva (spit). Cortisol is a hormone made by your adrenal glands, two small glands that sit above your kidneys. Hormones are chemical messengers in your bloodstream that control the actions of certain cells or organs. Cortisol affects almost every organ and tissue in your body. It helps your body:

• Respond to stress (cortisol is sometimes called the "stress hormone.")
• Reduce inflammation (swelling)
• Control blood glucose (also called "blood sugar") and metabolism (how your body uses food for energy)
• Control your blood pressure

Your pituitary gland, a gland in your brain, makes another hormone, called ACTH (adrenocorticotropic hormone). ACTH tells your adrenal glands how much cortisol to make. If your cortisol levels are too high or too low, it may mean you have a problem with your adrenal glands or your pituitary gland.

High cortisol levels may also be caused by a tumor that makes cortisol, or taking large doses of certain steroid medicines, such as prednisone, for a long time. Low levels may happen if you stop the medicine suddenly. Without treatment, cortisol levels that are too high or too low can be very serious.

Other names: urinary cortisol, salivary cortisol, free cortisol, blood cortisol, plasma cortisol, cortisol serum, 24-hour urinary cortisol excretion, 24-hour urinary free cortisol (UFC), late-night salivary cortisol, cortisol competitive protein binding assay, cortisol fluorometric assay

What is it used for?

A cortisol test is used to help diagnose or rule out medical conditions that cause too much or too little cortisol, such as:

• Cushing's syndrome, a disorder that causes high cortisol levels. It happens when your body has been exposed to too much cortisol for a long period of time. It may be caused by steroid medicines or certain tumors that cause your body to make extra cortisol.
• Addison disease, a condition that causes low cortisol levels. It happens when your adrenal glands can't make enough cortisol because certain infections or diseases have damaged them.
• Secondary adrenal insufficiency, a condition that causes low cortisol levels. It happens when your pituitary gland can't make enough ACTH to tell your adrenal glands to make cortisol. Over time, your adrenal glands may shrink and stop working.

Cortisol testing is also used to monitor treatment for these conditions.

Why do I need a cortisol test?

You may need a cortisol test if you have symptoms of a condition that affects cortisol levels.

• Symptoms of Cushing's syndrome (too much cortisol) may include:
  • Weight gain
  • Thin arms and legs
  • Round face
  • Increased fat around the base of your neck or between your shoulder blades
  • Easy bruising
  • Wide purple streaks on your stomach, breasts, hips, and under your arms
  • Muscle weakness
• Common symptoms of Addison disease and adrenal insufficiency (too little cortisol) may include:
  • Long-lasting fatigue
  • Muscle weakness
  • Loss of appetite
  • Weight loss
  • Abdominal (belly) pain

What happens during a cortisol test?

Most of your cortisol is in your blood, so cortisol tests often use a sample of blood drawn at a lab. But some cortisol passes into your urine and saliva. Measuring cortisol in these fluids is also an accurate way to estimate how much cortisol is in your blood.

Because cortisol levels vary during the day, your provider may ask you to collect a few saliva samples at home at different times. This is a convenient way to gather information about when your cortisol levels rise and fall. To learn more about your cortisol levels, your health care provider may order more than one type of test.

For a blood test, a health care professional will take a blood sample from a vein in your arm, using a small needle. After the needle is inserted, a small amount of blood will be collected into a test tube or vial. You may feel a little sting when the needle goes in or out. This usually takes less than five minutes.

Blood samples are usually taken twice during the day--once in the morning when cortisol levels are normally at their highest, and again around 4 p.m., when levels are normally much lower.

For a cortisol urine test, your provider may ask you to collect all your urine during a 24-hour period. This is called a "24-hour urine sample test." For this test, you'll be given a special container and instructions for how to collect and store your urine sample. Your provider will tell you what time to start. The test usually includes the following steps:

• To begin, urinate in the toilet as usual. Do not collect this urine. Write down the time you urinated.
• For the next 24 hours, collect all your urine in the container.
• Store the urine container in a refrigerator or in a cooler with ice during the collection period.
• 24 hours after starting the test, try to urinate if you can. This is the last urine collection for the test.
• Return the container with your urine to your provider's office or the laboratory as instructed.

In certain cases, a urine test for cortisol may be done on one sample of urine collected in the morning.

A cortisol saliva test may be done at your provider's office or at home with a kit you use to collect a saliva sample. Your sample may be collected with a swab, or you may spit into a tube.

If you're collecting your own sample, your provider will tell you what time to collect it. You may need to collect more than one sample. Many kits use a swab. Be careful to follow the instructions carefully. They usually include these general steps:

• Do not eat, drink, brush, or floss your teeth for 30 minutes before the test.
• Wash and dry your hands.
• Open the tube that holds the swab and let the swab fall into your mouth without touching it with your hands.
• Roll the swab in your mouth or hold it under your tongue for about 2 minutes until it is soaked with saliva.
• Spit the swab back into the tube without touching it and close the tube.
• Label the tube with the time you collected the sample.
• Take your saliva sample to your doctor's office or the lab as instructed.

Will I need to do anything to prepare for the test?

The preparations for a cortisol test will depend on the type of test you are having. Be sure to follow all the instructions that your provider gives you.

Stress and exercise can raise your cortisol levels, so you may need to rest before your test. For a blood test, you'll need two appointments at different times on the same day. Before a saliva test, you may need to stop using certain medicines. Let your provider know about all the medicines you use, including skin creams. But don't stop using any medicines without talking with your provider first.

Are there any risks to the test?

There is very little risk to having a blood test. You may have slight pain or bruising at the spot where the needle was put in, but most symptoms go away quickly.

There are no known risks to a urine or saliva test.

What do the results mean?

A cortisol test alone can't diagnose the cause of abnormal cortisol levels. If your cortisol level isn't normal, you will usually have more tests to find out what is causing the problem.

High levels of cortisol may be a sign that you have Cushing's syndrome. It may be caused by:

• Taking high doses of certain steroid medicines for a long time to treat conditions, such as asthma, rheumatoid arthritis, or lupus.
• Tumors that make extra ACTH, which tells your adrenal glands to make cortisol. These tumors may be in your pituitary gland or other parts of your body, including your lungs.
• Tumors in your adrenal glands that make extra cortisol.

Low levels of cortisol may mean you have Addison disease or secondary adrenal insufficiency:

• Common causes of Addison disease include damage to your adrenal glands from conditions, such as:
  • Autoimmune diseases
  • Certain infections, including tuberculosis (TB) and HIV
• Common causes of secondary adrenal insufficiency include:
  • Autoimmune diseases
  • Problems with your pituitary gland
  • Traumatic brain injury
  • Surgical removal of your pituitary gland to treat other conditions

If your cortisol results aren't normal, it doesn't always mean you have a medical condition that needs treatment. The most common cause of abnormal cortisol levels is taking steroid medicines for a long time or suddenly stopping them. Cortisol levels can also be affected by:

• Stress
• Pregnancy
• Exercise
• Hot and cold temperatures
• Certain medicines, such as birth control pills

To learn what your test results mean, talk with your provider.

Learn more about laboratory tests, reference ranges, and understanding results.

Is there anything else I need to know about a cortisol test?

High cortisol levels may come and go in some people. This is sometimes called pseudo-Cushing's syndrome, which means false Cushing's syndrome. It's also called "non-neoplastic hypercortisolism."

It may be caused by depression, anxiety, alcohol use disorder, poorly controlled diabetes, obesity, and other health problems. Tests to find the cause of high cortisol levels may help diagnose non-neoplastic hypercortisolism.