ACTH Stimulation Test

The ACTH stimulation test shows how well your adrenal glands are working. The adrenal glands are 2 glands that are above your kidneys. They make hormones (chemicals) that go into the blood. One of these hormones is cortisol. Cortisol helps the body respond to stress. If your adrenal glands are not working right, you may have too much or too little cortisol. 

BEFORE THE TEST

  • You may need to stop taking some medications before the test.  Give your caregiver a list of all medications you take. Include prescription and over-the-counter medicines. Also include herbs, vitamins, eyedrops, and medicated creams.

  • You may be asked to eat foods that contain carbohydrates the day before the test. Some examples are fruits, vegetables, breads, pastas, and milk.

  • Do not eat or drink for 6 hours before the test.

  • The test often is done in the early morning.  Arrive in time to fill out any needed paperwork.

HOW THE TEST IS DONE

Your blood will be taken and tested 2 times.  In between, you will be given a shot (injection) called cosyntropin. Cosyntropin makes the adrenal glands release cortisol. The whole test process usually takes a little more than an hour.  Then, the blood samples will be checked in a lab. This test will show the difference in the amount of cortisol in your blood before and after you were given cosyntropin.

  • To take a sample of your blood:

  • An area on your arm or hand will be cleaned with a germ-killing (antiseptic) swab.

  • An elastic band may be wrapped around your upper arm. This makes it easier for your caregiver to see veins under your skin.

  • A needle will be put into your vein. Blood from the needle will flow into a small bottle or tube. Then, the needle is taken out.

  • The band is taken off. The caregiver will press on the spot where the needle went in to stop any bleeding.

Other times, something called a heparin lock is used. Only one needle is used for this test. To do a heparin lock:

  • A small needle is put into your vein. Tape is put on your arm or hand to hold the needle in place.

  • For the first blood sample, the needle is hooked to a plastic tube. It is hooked to a different tube for the injection.  And, a new tube is used for the last blood test.

  • When the test is done, the needle is taken out. Pressure and a bandage are used to stop any bleeding.

Sometimes, a urine sample also is taken.  Cortisol levels can be checked in urine, too.

RISKS AND COMPLICATIONS

This is a simple and safe test.  Problems are rare.  But, they can occur. Possibilities include:

  • Bleeding at the spot where a needle was put in.

  • Bleeding or bruising under the skin (hematoma).

  • Fainting or feeling lightheaded.

  • Infection.

YOUR TEST RESULTS

  • It is your responsibility to obtain your test results. Ask the lab or department performing the test when and how you will get your results.

  • Cortisol levels in the blood normally go up after an ACTH stimulation test. The results are measured in micrograms per deciliter (mcg/dL). This tells how much (in micrograms) of cortisol there is in a certain amount (in deciliters) of blood.

  • Ranges for normal findings may vary among different laboratories and hospitals. You should always check with your doctor after having lab work or other tests done to discuss the meaning of your test results and whether your values are considered within normal limits.

  • Your caregiver will help you understand the results. Keep asking questions until it is clear to you.

  • Results may not be normal for different reasons. You might need more testing.