Patient education: Cortisol test (The Basics)

What is a cortisol test? — A cortisol test measures the amount of cortisol in the body. Cortisol is a hormone that helps the body work normally.

Cortisol is made in the "adrenal glands," which are small organs located on top of each kidney. Normally, the adrenal glands make cortisol after they receive signals from the pituitary gland. The pituitary gland is a small organ that is located just below the brain. Cortisol levels change throughout the day.

Cortisol is important for:

●Managing the body's reactions to stress

●Fighting infection

●Regulating blood glucose (sugar) levels

●Keeping blood pressure under control

●Metabolism – This is how the body uses energy.

Having too much or too little cortisol can lead to health problems.

Your cortisol level can be measured using a sample of blood, urine, or saliva (spit).

Why might I get a cortisol test? — Your doctor might order a cortisol test if you have symptoms of:

●Cushing syndrome – This is a disorder where the adrenal glands make too much cortisol. Symptoms can include weight gain in certain parts of the body, skin that bruises easily, oily skin or acne, diabetes, high blood pressure, or mood problems.

●Adrenal insufficiency – This is when the adrenal glands make too little cortisol. Several problems can cause adrenal insufficiency:

•Addison disease – This is a disorder where the adrenal glands are damaged and can't make enough cortisol. It is also called "primary" adrenal insufficiency. Symptoms can include feeling tired and weak, weight loss or loss of appetite, darkening of the skin in certain parts of the body, muscle and joint pain, and craving salt.

•Pituitary disease – If the pituitary gland is damaged, it cannot tell the adrenal gland to make cortisol. This is also called "secondary" or "central" adrenal insufficiency. Symptoms can include weakness, feeling very tired, and low blood sugar. Unlike Addison disease, it does not cause darkening of the skin or salt craving.

•Adrenal crisis – This is a life-threatening condition that can happen when levels of cortisol suddenly get very low. It can happen if you have untreated primary or secondary adrenal insufficiency. This causes your blood pressure to drop and can cause your body to go into shock. Symptoms can include vomiting, belly pain, weakness, fever, confusion, dizziness, and passing out.

Taking medicines called "steroids" for more than 3 weeks can cause you to have too much cortisol. But if you stop taking steroids too suddenly, this can cause you to have too little cortisol.

How do I prepare for a cortisol test? — For this test:

●You need to give a sample of urine, saliva, or blood. The type of sample you give depends on what problems you are being tested for.

●The sample is then tested in a lab to measure the amount of cortisol.

●Your doctor or nurse will tell you which type of test you are having, and exactly what you need to do to prepare for it.

For saliva or blood samples, they usually need to be collected at specific times, like early in the morning or late at night. This is because your cortisol levels change throughout the day. For example, blood samples are usually taken around 8:00 AM, and saliva samples are usually taken late at night. Sometimes, more than 1 sample is needed.

What happens during a cortisol test? — What happens during your test depends on the type of sample being collected.

If your urine is being tested:

●You will do a "24-hour urine collection." This means collecting all of your urine for a 24-hour period. Usually, you do this at home. Your doctor or nurse will give you instructions. You might need to do the 24-hour urine collection more than once, so your doctor can compare your results.

If your saliva is being tested:

●You will collect a sample of your saliva at home. Your doctor or nurse will tell you exactly how and when to do this. They will also give you the supplies.

If your blood is being tested:

●You will get a "blood draw." Your doctor or nurse will tell you where to go for this. For the blood draw, a needle is used to take a small amount of blood from your arm (figure 1). Collecting the blood only takes a few minutes. The blood is then tested in a lab.

●It might help to wear a short-sleeve shirt to your blood draw appointment. This makes it easier for the person drawing your blood to get to your arm.

●Tell the person who takes your blood:

•If you take "blood thinner" medicines or if you have a bleeding problem – They will make sure that your bleeding is under control before you leave.

•If you have a latex allergy – Some of the supplies used for blood draws might contain latex.

•If you have a preferred arm to use

●Most of the time, getting blood taken does not cause problems. You might have a little soreness or bruising where the needle went in.

What do my results mean? — Your doctor or nurse will tell you when to expect your results, and will contact you with the results. Or if you use an online "patient portal," you might get an alert there when your results are ready.

If your cortisol test shows any abnormal results, your doctor or nurse will talk to you about what to do next. They might need to do more tests to figure out what the cause is.

If you do have a health problem, your doctor will work with you to come up with a plan for treatment.

More on this topic

Patient education: 24-hour urine collection (The Basics)
Patient education: Cushing syndrome (The Basics)
Patient education: Addison disease (The Basics)
Patient education: Adrenal crisis (The Basics)
Patient education: Adrenal cancer (The Basics)

Patient education: Collection of a 24-hour urine specimen (Beyond the Basics)
Patient education: Cushing syndrome (Beyond the Basics)
Patient education: Cushing syndrome treatment (Beyond the Basics)
Patient education: Adrenal insufficiency (Beyond the Basics)