Other names: Corticotropin; Adrenocorticotropic Hormone.

This test is used to measure the levels of adrenocorticotropic hormone (ACTH) in the bloodstream. ACTH is important because it encourages the production of cortisol, which is a steroid hormone that controls the metabolism of glucose, proteins and lipids; cortisol also helps to regulate blood pressure and suppress harmful immune system reactions.

Why is the test used?

The ACTH test is used to test for diseases that are associated with the adrenal and pituitary glands; examples of these conditions include Cushing’s syndrome, Addison’s disease, adrenal tumours and pituitary tumours.

The test can also be used to help doctors monitor the effects of drugs given to patients to help increase or decrease cortisol production; this can often help doctors to reach an accurate diagnosis.

Why would I have the test?

Your doctor may recommend that you have the ACTH test if you are experiencing symptoms associated with producing too much or not enough cortisol; doctors may also recommend the test for patients who have symptoms of a hormone imbalance, which is causing problems related to the function of the adrenal and pituitary glands.

How is the test performed?

The ACTH test is done by collecting a blood sample from a vein in the arm. The doctor will place a tourniquet around the upper arm to encourage the veins in the arm to swell; this will make it easier for the doctor to insert a needle into the vein. Once the needle has been inserted, the syringe will be drawn back and the blood will fill the syringe. Once the sample has been collected, it will be bottled, labelled and sent away to the laboratory.

It is necessary to fast for a period of time before the test is carried out; most blood tests are carried out very early in the morning so you will be required to fast over night.

What does the test result signify?

The levels of cortisol and ACTH are measured together; certain levels of each hormone may indicate different conditions, as outlined below:

  • Cushing’s syndrome: high cortisol, high ACTH
  • Adrenal tumour: high cortisol, low ACTH
  • Addison’s disease: low cortisol, high ACTH
  • Ectopic ACTH (this is when a tumour outside of the pituitary gland makes ACTH): high cortisol, high ACTH
  • Hypopituitarism (decreased function of the pituitary gland): low cortisol, low ACTH

The levels of cortisol and ACTH vary according to the time of day; usually levels are higher in the morning.

Specific Blood Tests

© Medic8® | All Rights Reserved