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Adrenocorticotropic Hormone Stimulation Test

(ACTH Cosyntropin Stimulation Test)

Pronounced: a-DREE-no-kor-TEE-ko-tro-pic hor-moan stim-U-lay-shun test

What Is Adrenocorticotropic Hormone (ACTH)?

ACTH is a hormone made by the pituitary gland. It regulates the amount of cortisol made by the adrenal glands. Cortisol is a hormone that regulates blood pressure and other bodily functions.

Reason for the Test

This test measures the amount of ACTH in your blood to find out if your adrenal glands are making enough cortisol.

Type of Sample Taken

A blood sample is taken from a vein in the arm.

Prior to Collecting the Sample

You may be asked not to eat or drink the night before your test.

Talk to your doctor about any medicines you take. Some may affect test results, such as hydrocortisone and other glucocorticoids. These must be stopped several days before the test.

During the Sample Collection

Often, a morning cortisol level is taken to find out if baseline levels are normal.

The test looks at cortisol levels in your blood before you get an injection of a synthetic ACTH called cosyntropin. It looks at them again 30 and 60 minutes after to find out how your body responds.

You will be asked to sit. An area near the bend in your arm will be cleaned with a wipe. A large band will be tied around your arm. The needle will be put in a vein. A tube will collect the blood from the needle. The band on your arm will be taken off. After the blood is collected, the needle will be removed. Gauze will be held on the site to help stop bleeding. You may also be given a bandage. This test takes about 5 to 10 minutes. This process will be repeated 30 and 60 minutes later.

After Collecting the Sample

After the blood sample is taken, you may need to stay seated for 10 to 15 minutes. If you are lightheaded, you may need to stay seated longer. When you feel better, you can leave.

A bit of blood may ooze from the vein beneath the skin. It will cause a bruise. A bruise will usually fade in a day or 2.

Call your doctor right away if you have redness, swelling, lasting bleeding, or pain.

Results

It will take about a day to get your test results.

Cortisol is created by the adrenal glands in response to ACTH. It is normal for cortisol levels to increase after the injection. The highest blood concentration of cortisol from the 3 blood samples is the one used to find out if the test shows a normal adrenal gland response. Abnormal results may point to:

  • Addison disease—autoimmune destruction of the adrenal glands
  • Pituitary gland problems

Talk to your doctor about your test results. A test may point to an illness that you do not have. It can also miss an illness that you may have. The doctor will check your symptoms and all test results before making a diagnosis.

REFERENCES:

ACTH. Lab Tests Online—American Association for Clinical Chemistry website. Available at: https://labtestsonline.org/understanding/analytes/acth/tab/glance. Updated June 5, 2019. Accessed August 1, 2019.

Adrenal insufficiency in adults. EBSCO DynaMed website. Available at:http://www.dynamed.com/topics/dmp~AN~T116703/Adrenal-insufficiency-in-adults. Updated July 24, 2018. Accessed August 1, 2019.

Corticotropin-releasing hormone stimulation test. EBSCO DynaMed website. Available at:http://www.dynamed.com/topics/dmp~AN~T906829/Corticotropin-releasing-hormone-stimulation-test. Updated October 8, 2018. Accessed August 1, 2019.

Van Leeuwen AM, Bladh ML. Cortisol and challenge tests. Davis's Comprehensive Handbook of Laboratory & Diagnostic Tests with Nursing Implications, 6th ed. 2015:608-617. Available at:https://www.ebscohost.com/nursing/products/nursing-reference-center. Accessed August 1, 2019.

Last reviewed June 2019 by EBSCO Medical Review Board Daniel A. Ostrovsky, MD