This test measures the amount of adrenocorticotropic hormone, known as ACTH, in the blood. ACTH is a hormone made 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 whose hormone levels are not in a healthy range. A doctor may suspect a link with problems 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 called a 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 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 After the needle is withdrawn, the puncture site is covered for a short time to prevent bleeding.