Information About Adrenocorticotropic Hormone Test (ACTH)

Submitted on March 27, 2012

ACTH stimulation test is done to measure the adrenocorticotropic hormone in the blood. The level of this hormone can help doctors identify problems in the adrenal glands or the pituitary gland. The pituitary gland makes ACTH, in response to another hormone, corticotropin-releasing hormone (CRH) that is released by the hypothalamus. Then the adrenal glands create cortisol, a hormone that manages stress in our bodies. An increase in the cortisol levels can decrease the level of ACTH, and vice versa.

The level of both these hormones changes through the day. There is a high level of ACTH in the morning and low level of it in the evening. An endocrinologist needs to interpret the test results.

Reasons Why It is Done

These tests are done to ascertain and identify -

  • A problem in the pituitary gland or in the adrenal glands.
  • If too much of ACTH is being produced, then doctors need to check if that is due to an overactive pituitary gland. Then too much of cortisol is released by the adrenal glands, and this could be a form of Cushing's syndrome.


You should not drink or eat anything for 10-12 hours before you have an ACTH test. You may be asked by a health care professional to be on a low-carbohydrate diet for 48 hours. You can consult with your doctor about any other food products that you should avoid.

Medicines can alter the test results. So make sure you tell your doctor about any medicines that you are taking at the moment. You should avoid exercising for at least 12 hours before the blood test, and try to keep away from emotional stress or stressful situations for the same timeframe.

Generally, blood samples are collected in the morning as ACTH levels are high at this time and the timing is important for accurate results. You may need to do your test in the evening if the physician wants a low ACTH level.


A health professional will follow the standard procedure of drawing blood.

Risks involved

There's hardly any risk if the blood is drawn with a clean needle and in the right manner. Your arm may feel sore or there might be a red patch in the area. You can use a warm compress for relief.


You can get the results within four to six days. We suggest that you speak with your health professional or your doctor for in-depth information about the condition and the procedure.