Cortisol blood test

A cortisol test is done to find problems of the pituitary gland or adrenal glands, such as making too much or too little hormones.

A health professional uses a needle to take a blood sample, usually from the arm.

You may be asked to avoid strenuous physical activity the day before a cortisol test. You may also be asked to lie down and relax for 30 minutes before the blood test.

Some medicines, such as steroids, can affect cortisol levels for some time even after you stop taking the medicine.

Normal

Each lab has a different range for what's normal. Your lab report should show the range that your lab uses for each test. The normal range is just a guide. Your doctor will also look at your results based on your age, health, and other factors. A value that isn't in the normal range may still be normal for you.

High values

• A high level of cortisol in the blood can mean Cushing's syndrome, a disorder that can be caused by overactive adrenal glands, an adrenal gland tumor, some types of cancer, or long-term use of corticosteroids.
• A high blood cortisol level can be caused by severe liver or kidney disease, depression, hyperthyroidism, or obesity.
• Pregnancy or birth control pills can also cause a high blood cortisol level.
• Conditions such as recent surgery, illness, injury, or whole-body infection (sepsis) can cause high cortisol levels.

Low values

• A low level of cortisol in the blood can be caused by:
  • Problems that affect the adrenal glands directly, such as Addison's disease or a tuberculosis infection of the adrenal glands.
  • Problems with the pituitary gland that affect the adrenal glands, such as cancer or a head injury.