What is a cortisol test?
A cortisol test measures the level of cortisol in your body. Cortisol is a hormone made by your adrenal glands. The test determines whether you have too much or too little of the hormone.
The test requires a sample of blood, urine, saliva or a combination. The results can help healthcare providers diagnose:
- Addison’s disease, also known as hypocortisolism or primary adrenal insufficiency. This condition happens when your body has too little cortisol.
- Cushing’s syndrome, also called hypercortisolism. The condition occurs when your body has too much cortisol.
- Tumor affecting the production of cortisol. Various tumors may cause high cortisol levels.
A cortisol test is sometimes called:
- Free cortisol.
- Salivary cortisol.
- Urinary cortisol.
What is cortisol?
Cortisol is a hormone made by the adrenal glands. It’s nicknamed the stress hormone because it helps you respond to stress. It also helps you:
- Fight infection.
- Maintain blood pressure.
- Regulate blood sugar and metabolism (how your body processes food to create energy).
Most cortisol is in the blood, attached to proteins. But some cortisol is “free” and present in the urine and saliva.
In a healthy person, cortisol rises and falls at different times of the day. It’s usually higher in the morning and lower at night unless a person works late or has changing shifts. Other events or factors can affect cortisol levels, including:
- Infection, injury or disease.
- Medications such as hydrocortisone, prednisone or birth control pills.
- Physical or emotional stress.
What does a cortisol test show?
A cortisol test shows whether a person has high or low levels of cortisol, which may indicate an adrenal disorder.
A normal cortisol value in a blood sample taken at 8 a.m. is 5 to 25 mcg/dL. But results can vary widely, depending on the time of the test and the other factors that affect cortisol levels.
What are the symptoms of high cortisol levels?
The symptoms of Cushing’s syndrome include:
- Changes in sex drive.
- Excessive hair growth or balding.
- High blood pressure (hypertension).
- Purple stretch marks over the abdomen.
- Red, round face.
- Wounds that heal poorly.
- Easy bruising on the arms and legs.
- Weak muscles and thinner arms and legs.
- Stunted growth in children.
- Weight gain.
- Mood swings.
- Increased fracture risk and weaker bones.
- Increased risk of blood clots.
What are the symptoms of low cortisol levels?
The symptoms of Addison’s disease include:
- Abdominal pain.
- Abnormal menstrual periods.
- Cravings for salty food, loss of appetite or unexplained weight loss.
- Low blood glucose (hypoglycemia).
- Low blood pressure (hypotension).
- Muscle weakness, especially climbing stairs and combing hair.
- Nausea and vomiting or diarrhea.
- Patches of dark skin, darkening of lips, gums and palms.
How does a cortisol test work?
Cortisol can be measured in the blood, urine, saliva or a combination. Your healthcare provider will tell you which test they recommend for you.
- Blood test: In an office, clinic or lab, a healthcare provider inserts a thin needle into a vein in your arm. The needle collects a small sample of blood into a tube. You might feel a slight sting when the needle goes in.
- Saliva test: You or a healthcare provider puts a swab in your mouth and waits a few minutes until the swab is saturated with spit. If you do the test yourself at home, your healthcare provider will give you a special kit. They’ll tell you what time to perform the test and how to return the sample.
- Urine test: Your healthcare provider gives you a container to collect your pee. Most urinary cortisol tests collect all the pee you produce in 24 hours. Your healthcare provider may ask you to store the urine in a cold place, then return it to their office or a lab.
You may need to repeat cortisol testing twice in one day or multiple times over several days because cortisol levels vary.
How do I prepare for a cortisol test?
Your healthcare provider will give you specific instructions. For example, you shouldn’t eat, drink or brush your teeth before a salivary test. You may need to rest beforehand so that stress doesn’t interfere with the results.
What are the risks of a cortisol test?
Blood tests involve minimal risk. Urine and saliva tests have no known risks.
Results and Follow-Up
When will I get the results of a cortisol test?
Cortisol test results may take one to five days, depending on the healthcare provider and lab.
What do cortisol test results mean?
The outcome of cortisol testing can indicate several different things. Your healthcare provider will explain your results and what they mean.
High levels of cortisol might indicate:
- Effects of large amounts of certain medications.
- Tumor in your pituitary gland that’s producing adrenocorticotropic hormone (ACTH), which stimulates the production of cortisol.
- Tumor in your adrenal gland that’s producing too much cortisol.
- Tumor elsewhere in your body, such as small cell lung cancer.
Low levels of cortisol might indicate:
- Tumor in your pituitary gland tumor that slows ACTH production.
- Underactive or damaged adrenal glands.
- Underactive pituitary gland.
If your results are low or high, your healthcare provider may order other tests:
- ACTH stimulation test: This assesses how your adrenal glands respond after you get a shot of artificial ACTH.
- Dexamethasone suppression test: This measures cortisol after you take a medication called dexamethasone, a manufactured version of cortisol.
- Imaging tests: An MRI or CT scan allows healthcare providers to take pictures of your glands and locate a possible tumor.
A note from Cleveland Clinic
A cortisol test measures the level of cortisol in your body. It can help diagnose an adrenal disorder such as Cushing’s syndrome or Addison’s disease. Your healthcare provider will give you specific instructions on the type of test you need and when it should happen.
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