Health Encyclopedia

ACTH (cosyntropin) stimulation test

Definition

ACTH (cosyntropin) stimulation test measures how well the adrenal glands respond to the hormone ACTH. ACTH is a hormone produced in the pituitary gland that stimulates the adrenal glands to release cortisol.

Alternative Names

Tests of adrenal reserve; Cortrosyn stimulation test

How the test is performed

The health care provider will measure the cortisol in your blood before and after an ACTH injection.

Blood is typically drawn from a vein, usually on the inside of the elbow or the back of the hand. The site is cleaned with germ-killing medicine (antiseptic). The health care provider wraps an elastic band around the upper arm to apply pressure to the area and make the vein swell with blood.

Next, the health care provider gently inserts a needle into the vein. The blood collects into an airtight vial or tube attached to the needle. The elastic band is removed from your arm. Once the blood has been collected, the needle is removed, and the puncture site is covered to stop any bleeding.

In infants or young children, a sharp tool called a lancet may be used to puncture the skin and make it bleed. The blood collects into a small glass tube called a pipette, or onto a slide or test strip. A bandage may be placed over the area if there is any bleeding.

Once the blood has been collected, the health care provider will use a needle to inject cosyntropin. Other timed specimens are also collected.

Along with the blood tests, sometimes you may also have a urinary free cortisol test or urinary 17-ketosteroids test in which the urine is collected over a 24-hour period.

How to prepare for the test

You may need to limit activities and eat a high-carbohydrate diet 12-24 hours before the test. You may be asked to fast for 6 hours before the test.

How the test will feel

When the needle is inserted to draw blood, some people feel moderate pain, while others feel only a prick or stinging sensation. Afterward, there may be some throbbing.

Why the test is performed

This test can help determine whether your adrenal and pituitary glands are normal. It is most often used when the health care provider suspects adrenal gland disorders, such as Addison's disease or pituitary insufficiency.

Normal Values

An increase in cortisol after stimulation by ACTH is normal. Blood cortisol after ACTH stimulation should be greater than 18 - 20 mcg/dL, depending on the dose of cosyntropin used.

Note: mcg/dL = micrograms per deciliter

Normal value ranges may vary slightly among different laboratories. Talk to your doctor about the meaning of your specific test results.

What abnormal results mean

This test is helpful in determining if you have:

Acute adrenal crisis
Addison's disease (decreased adrenal output)
Low pituitary function
Pituitary tumors

What the risks are

Veins and arteries vary in size from one patient to another and from one side of the body to the other. Obtaining a blood sample from some people may be more difficult than from others.

Other risks associated with having blood drawn are slight but may include:

Excessive bleeding
Fainting or feeling light-headed
Hematoma (blood accumulating under the skin)
Infection (a slight risk any time the skin is broken)

References

Stewart PM. The Adrenal Cortex. In: Kronenberg HM, Melmed S, Polonsky KS, Larsen PR. Kronenberg: Williams Textbook of Endocrinology. 11th ed. Philadelphia, PA: Saunders Elsevier; 2008:chap 14.

Melmed S, Kleinberg D. Anterior Pituitary. In: Kronenberg HM, Melmed S, Polonsky KS, Larsen PR. Kronenberg: Williams Textbook of Endocrinology. 11th ed. Philadelphia, PA: Saunders Elsevier; 2008:chap 8.

Review Date:3/18/2008
Reviewed By:Elizabeth H. Holt, MD, PhD, Assistant Professor of Medicine, Section of Endocrinology and Metabolism, Yale University. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.

ADAM Quality A.D.A.M., Inc. is accredited by URAC, also known as the American Accreditation HealthCare Commission (www.urac.org). URAC's accreditation program is the first of its kind, requiring compliance with 53 standards of quality and accountability, verified by independent audit. A.D.A.M. is among the first to achieve this important distinction for online health information and services. Learn more about A.D.A.M.'s editorial process. A.D.A.M. is also a founding member of Hi-Ethics (www.hiethics.com) and subscribes to the principles of the Health on the Net Foundation (www.hon.ch).

The Agency for Health Care Administration (Agency) and this website do not claim the information on, or referred to by, this site is error free. This site may include links to websites of other government agencies or private groups. Our Agency and this website do not control such sites and are not responsible for their content. Reference to or links to any other group, product, service, or information does not mean our Agency or this website approves of that group, product, service, or information.

Additionally, while health information provided through this website may be a valuable resource for the public, it is not designed to offer medical advice. Talk with your doctor about medical care questions you may have.