Alternative Names serum adrenocorticotropic hormone, adrenocorticotropic hormone
Definition This test measures the amount of adrenocorticotrophic hormone (ACTH) in the blood. ACTH is a hormone secreted by the pituitary gland. It regulates the production and secretion of the hormone cortisol by the adrenal gland.
Who is a candidate for the test? This test is normally performed on persons with a possible hormone problem. A doctor may suspect a problem specifically in the pituitary gland or the adrenal gland.
How is the test performed? To measure ACTH levels, a blood sample is taken from a vein on 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 restricts blood flow in the veins in the lower arm and enlarges 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 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 After the needle is withdrawn, the puncture site is covered for a short time to prevent bleeding.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? The doctor will provide specific instructions. Generally, no preparation is required.
What do the test results mean? Normal levels of ACTH in the blood may range from 2 to 12 pmol/L (picomoles per litre).
High levels of ACTH may be caused by:
abnormally decreased functioning in the adrenal glands, such as Addison's disease
abnormally increased functioning in the adrenal glands, such as Cushing's syndrome
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
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