An ACTH (adrenocorticotropic hormone) blood test measures the level of ACTH in the blood. ACTH is a hormone produced by the pituitary gland that stimulates the production of cortisol by the adrenal glands. Cortisol is a hormone that helps the body respond to stress, regulates blood sugar levels, and affects the immune system.

An ACTH blood test is typically used to help diagnose and monitor medical conditions that affect the production and regulation of cortisol, such as Addison’s disease, Cushing’s syndrome, and pituitary tumors. The test may also be ordered to help diagnose and monitor conditions that affect the adrenal glands, such as congenital adrenal hyperplasia.

During the test, a small sample of blood is taken from a vein in the arm and sent to a laboratory for analysis. The normal range for ACTH levels in the blood varies depending on the time of day and other factors, but generally falls between 9 and 52 picograms per milliliter (pg/mL).

Abnormal ACTH levels can provide important information about the health of an individual. For example, low levels of ACTH may be a sign of adrenal insufficiency, a condition in which the adrenal glands do not produce enough cortisol. High levels of ACTH may be a sign of Cushing’s syndrome, a condition in which the body produces too much cortisol.

It is important to note that ACTH levels can be affected by a variety of factors, such as stress, illness, and certain medications. Therefore, it is important to discuss any abnormal results with a healthcare provider who can interpret the results in the context of the individual’s medical history and other test results.