Cortisol, Serum (Mass Concentration)

Cortisol is a hormone made by your adrenal glands that helps your body respond to stress, control blood pressure, and manage how it uses energy. Your doctor may order this test to check whether your adrenal or pituitary glands are working properly, or to help investigate symptoms such as fatigue, unexplained weight changes, or high blood sugar.

Your healthcare provider may order a cortisol test to check for adrenal gland issues, such as Cushing’s syndrome (too much cortisol) or Addison’s disease (too little cortisol). It can also help diagnose conditions like pituitary disorders or evaluate responses to stress or medications.

This test usually involves a simple blood draw from a vein in your arm, which takes only a few minutes. Depending on what your doctor is evaluating, it may also be done using a saliva sample or a 24-hour urine collection, and sometimes more than one sample is taken at different times of the day.

A blood sample is taken from a vein, usually in your arm. The blood is then processed to separate serum (the liquid part without clots) for testing. Results are typically available within a few days.

Because cortisol levels naturally rise and fall throughout the day, your doctor will tell you exactly when your sample needs to be taken. You may be asked to avoid strenuous exercise, certain medicines such as steroids or birth control pills, and stressful activities beforehand. Always tell your care team about every medication and supplement you take.

No special preparation is usually needed, but if you’re taking medications that affect cortisol levels (like steroids), your provider may ask you to stop them temporarily or adjust timing. Avoid caffeine or alcohol before the test, as they can influence results.

After a blood draw, you may have slight soreness or a small bruise where the needle was inserted, and this usually goes away within a day or two. You can normally return to your regular activities right away. Your doctor will contact you with the results and explain what they mean and whether any follow-up is needed.

You may experience mild bruising, soreness, or swelling at the injection site. Apply gentle pressure to the area to help reduce discomfort. Contact your provider if you notice unusual bleeding, pain, or signs of infection.