Adrenocorticotropic Hormone (ACTH) Measurement

Your doctor may order an ACTH test to help find the cause of symptoms that suggest your adrenal or pituitary glands are not working properly. It is often used to evaluate conditions such as Cushing syndrome, Addison disease, or unexplained fatigue, weight changes, low blood pressure, or abnormal cortisol levels.

Your doctor may order an ACTH test to diagnose or monitor conditions like Cushing’s disease (overproduction of cortisol), adrenal insufficiency (underproduction of cortisol), or to check for pituitary tumors. It can also help evaluate symptoms such as unusual weight gain, fatigue, or high blood pressure that may be linked to hormone imbalances.

Before the test, your healthcare provider will explain the procedure and give you specific instructions. Because ACTH levels naturally rise and fall throughout the day, the blood sample is often drawn in the early morning. You may be asked to avoid certain medications, strenuous exercise, or food for a short period beforehand.

No special preparation is usually needed, but your doctor might advise you to avoid certain medications or activities for a few days before testing. For example, they may suggest stopping steroids (like prednisone) if you’re taking them for a condition like asthma or arthritis, as these can affect ACTH levels.

During the test, a healthcare professional will clean the skin on your arm, wrap a band around your upper arm, and draw a small sample of blood from a vein using a thin needle. The procedure usually takes only a few minutes, and you may feel a brief pinch or sting. Afterward, a small bandage is placed over the site.

A blood sample will be taken from a vein in your arm. You may feel a slight pinch when the needle is inserted, but the procedure is quick and usually painless. The sample is then sent to a lab for analysis.

Your results show how much ACTH is in your blood. High levels may point to an adrenal gland problem such as Addison disease, while low levels may suggest an issue with the pituitary gland or Cushing syndrome. Your doctor will interpret your results alongside cortisol levels and other tests before making a diagnosis.

Results are interpreted by your doctor based on your symptoms, medical history, and other tests. High ACTH levels may suggest conditions like Cushing’s disease or pituitary tumors, while low levels might indicate adrenal insufficiency or other hormonal disorders. Your doctor will discuss the results with you in detail.