This test measures the amount of adrenocorticotrophic hormone, abbreviated as ACTH, in the blood.
This test is normally performed on persons with whose hormone levels are not in a healthy range. A doctor may suspect that a problem in the pituitary gland is linked to malfunction of the adrenal gland.
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 After the needle is withdrawn, the puncture site is covered for a short time to prevent bleeding.
The healthcare professional will provide specific instructions. Generally, no preparation is required.
Healthy levels of ACTH in the blood vary widely depending on the time of day and the person's clinical situation.
Higher than expected levels of ACTH may be caused by: a slowdown in functioning of the adrenal glands, such as Addison diseasepituitary gland tumor, which is an abnormal growth in the pituitary glandother tumors that produce excess ACTH
Lower than expected levels of ACTH can be caused by: excess production of cortisol by the adrenal glands, which occurs in conditions such as Cushing syndromecertain tumors of the adrenal glandvarious diseases of the pituitary gland