Alternative Names cortrosyn stimulation test, tests of adrenal reserve
Definition This test checks how the adrenal glands respond to a certain hormone. The hormone is called adrenocorticotrophic hormone, or ACTH. ACTH is made in the pituitary gland and travels through the bloodstream to the adrenal glands. ACTH stimulates the adrenal gland to release cortisol. Cortisol is important for many functions in the body's metabolism of fats, carbohydrates, sodium, potassium, and protein.
Who is a candidate for the test? This test is ordered when the doctor suspects that a person's adrenal gland is not working properly.
How is the test performed? Cortisol levels in the bloodstream are measured before and after an intravenous or intramuscular injection of ACTH. A blood sample is taken from a vein in the forearm or hand. First, the skin over the vein is cleaned with an antiseptic. Next, a strong rubber tube, or tourniquet, is wrapped around the upper arm. This enlarges the veins in the lower arm by restricting blood flow through them. A fine needle is gently inserted into a vein, and the tourniquet is removed. Blood flows from the vein through the needle, and is collected in a syringe or vial for testing in the laboratory. After the needle is withdrawn, the puncture site is covered for a short time to prevent bleeding.
What is involved in preparation for the test? A person should request specific instructions from his or her doctor.
What do the test results mean? Normally, an injection of ACTH will stimulate the adrenal glands. There will be an increase in cortisol.
If cortisol levels do not rise after the injection of ACTH, the following conditions may be present:
Addison's disease, which is caused by a deficiency of adrenocortical hormones after the adrenal gland is damaged
Cushing's syndrome, which is caused by an excess of adrenocortical hormones
hypopituitarism, which is caused by a decrease in hormones produced by the pituitary gland
pituitary tumour, or an abnormal growth in the pituitary gland
acute adrenal crisis, which is a condition in which the adrenal glands suddenly stop working properly
Author: David T. Moran, MD Reviewer: eknowhow Medical Review Panel Editor: Dr John Hearne Last Updated: 15/03/2005 Contributors Potential conflict of interest information for reviewers available on request
