ACTH Stimulation Test

The ACTH stimulation test determines how well the adrenal glands react to adrenocorticotropic hormonal agent (ACTH). ACTH is a hormonal agent produced in the pituitary gland that promotes the adrenal glands to release a hormone called cortisol.

The ACTH test (also called the cosyntropin, tetracosactide, or Synacthen test) is a medical test normally purchased and analyzed by endocrinologists to assess the functioning of the adrenal glands stress reaction by determining the adrenal reaction to adrenocorticotropic hormone (ACTH; corticotropin) or another corticotropic representative such as tetracosactide (cosyntropin, tetracosactrin; Synacthen) or alsactide (Synchrodyn). ACTH is a hormone produced in the anterior pituitary gland that stimulates the adrenal glands to launch cortisol, dehydroepiandrosterone (DHEA), dehydroepiandrosterone sulfate (DHEA-S), and aldosterone. (wikipedia)

How the ACTH Stim Test is Performed?

The test is done the following way:

  • Your blood is drawn.
  • You then receive a shot (injection) of ACTH, typically into the muscle in your shoulder. The ACTH may be a manufactured (artificial) type.
  • After either 30 minutes or 60 minutes, or both, depending upon how much ACTH you get, your blood is drawn again.
  • The laboratory checks the cortisol level in all the blood samples.

You might likewise have other blood tests, including ACTH, as part of the first blood test. In addition to the blood tests, you might also have a urine cortisol test or urine 17-ketosteroids test, which includes gathering the urine over a 24-hour period.

How to Prepare for Cosyntropin Stimulation Test

You might have to limit activities and eat foods that are high in carbohydrates 12 to 24 hours before the test. You might be asked to fast for 6 hours before the test. Sometimes, no special preparation is required. You may be asked to briefly stop taking medicines, such as hydrocortisone, which can hinder the cortisol blood test.

How the Test will Feel

When the needle is placed to draw blood, some people feel moderate pain. Others feel just a prick or stinging. Afterward, there may be some throbbing or small bruising. This quickly goes away.

The injection into the shoulder may cause moderate pain or stinging.

Some people feel flushed, anxious, or nauseated after the injection of ACTH.

Why the Test is Performed

This test can help figure out whether your adrenal and pituitary glands are normal. It is usually used when the doctor believes you have an adrenal gland issue, such as Addison disease, or pituitary insufficiency. It is also used to see if your pituitary and adrenal glands have actually recovered from prolonged use of glucocorticoid medications, such as prednisone.

Normal Results for Adrenal Reserve (ACTH Stim) Test

An increase in cortisol after stimulation by ACTH is normal. Cortisol level after ACTH stimulation ought to be higher than 18 to 20 mcg/dL, depending upon the dose of ACTH used.

Normal value ranges might differ somewhat amongst various laboratories. Some labs use various measurements or may test different specimens. Talk to your doctor about the meaning of your particular test outcomes.

What Abnormal Results Mean

This test is helpful in learning if you have:

  • Intense adrenal crisis (lethal condition that occurs when there is not enough cortisol).
  • Addison disease (adrenal glands do not produce sufficient cortisol).
  • Hypopituitarism (pituitary gland is not producing enough hormones such as ACTH).


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

Other risks connected with having actually blood drawn are slight however may consist of:

  • Excessive bleeding.
  • Passing out or feeling lightheaded.
  • Hematoma (blood collecting under the skin).
  • Infection (a slight risk whenever the skin is broken).


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