Also Known As
Corticotropin
Cosyntropin
Formal Name
Adrenocorticotropic hormone
This article was last reviewed on
This article waslast modified on
22 April 2018.
At a Glance
Why Get Tested?

To diagnose adrenal and pituitary diseases such as Cushing's syndrome, Cushing’s disease, Addison’s disease, adrenal tumours, and pituitary tumours; usually done as a diagnostic test once an abnormal cortisol level is detected

When To Get Tested?

If your doctor has discovered that you have abnormal cortisol levels.  ACTH will help to sort out the possible cause of the abnormal cortisol result.

Sample Required?

A blood sample taken from a vein in your arm

Test Preparation Needed?

The sample is unstable so needs to be collected in a hospital that has laboratory facilities to process it immediately. It cannot usually be collected at a GP surgery. Typically it is taken in the morning, about 9 am.

On average it takes 7 working days for the blood test results to come back from the hospital, depending on the exact tests requested. Some specialist test results may take longer, if samples have to be sent to a reference (specialist) laboratory. The X-ray & scan results may take longer. If you are registered to use the online services of your local practice, you will be able to access your results online.

If the doctor wants to see you about the result(s), you will be offered an appointment. If you are concerned about your test results, you will need to arrange an appointment with your doctor so that all relevant information including age, ethnicity, health history, signs and symptoms, laboratory and other procedures (radiology, endoscopy, etc.), can be considered.

Lab Tests Online-UK is an educational website designed to provide patients and carers with information on laboratory tests used in medical care. We are not a laboratory and are unable to comment on an individual's health and treatment.

Reference ranges are dependent on many factors, including patient age, gender, sample population, and test method, and numeric test results can have different meanings in different laboratories.

For these reasons, you will not find reference ranges for the majority of tests described on this web site. The lab report containing your test results should include the relevant reference range for your test(s). Please consult your doctor or the laboratory that performed the test(s) to obtain the reference range if you do not have the lab report.

For more information on reference ranges, please read Reference Ranges and What They Mean.

What is being tested?

Adrenocorticotropic hormone (ACTH) is a hormone produced in the pituitary gland (located below the brain within the skull) to stimulate secretion of the hormone cortisol by the adrenal glands (small organs located at the top of each kidney). Stress can stimulate the release of ACTH. Cortisol is important for regulating glucose, protein, and lipid metabolism; suppressing the immune response; and maintaining blood pressure. Normally, ACTH concentration increases when cortisol is low and falls when cortisol is high.

How is the sample collected for testing?

A blood sample is taken by needle from a vein in the arm.

Is any test preparation needed to ensure the quality of the sample?

The sample is unstable so needs to be collected in a hospital that has laboratory facilities to process it immediately. It cannot usually be collected at a GP surgery. Typically it is taken in the morning, about 9 am.

Accordion Title
Common Questions
  • How is it used?

    ACTH levels in the blood are tested to help diagnose Cushing's syndrome (see below), Addison's disease (see below), and tumours of the pituitary and adrenal glands. Measuring both ACTH and cortisol can help sort out some of the causes of these conditions. Because the level of ACTH normally changes in the opposite direction to the level of cortisol, your doctor can learn much by identifying an imbalance in this relationship and the direction in which the imbalance occurs. For example, if your cortisol level is high and your ACTH level is also increased, that would indicate that there is a pituitary disease that causes production of too much ACTH.

    The table below indicates the common patterns of ACTH and cortisol in different diseases involving the adrenal and pituitary glands. 
     

    Disease Cortisol ACTH
    Cushing's disease (pituitary tumour making ACTH) High High
    Adrenal tumour High Low
    "Ectopic" ACTH (ACTH made by a tumour outside the pituitary, usually in the lung) High High
    Addison's disease (adrenal damage) Low High
    hypopituitarism Low Low
  • When is it requested?

    This test is requested when a patient has signs or symptoms of certain diseases, including Cushing's syndrome or Addison's disease and has abnormal blood cortisol levels.

    Cushing's syndrome, caused by too much cortisol, can cause symptoms such as obesity, a rounded face, fragile and thin skin, purple lines on the tummy, muscle weakness, acne, and increased body hair. It is often seen with other physical and laboratory signs, including high blood pressure, low potassium, high bicarbonate, and high glucose (or even diabetes). Cushing's disease refers to Cushing's syndrome due to a tumour in the pituitary gland that makes ACTH. Other causes of Cushing's syndrome include adrenal tumours that make cortisol, tumours in other parts of the body (usually the lungs) that make ACTH (which then stimulates the adrenal glands to make cortisol), and taking high dose steroids prescribed by your doctor.

    Addison's disease is due to a lack of cortisol, and is seen with symptoms such as muscle weakness, tiredness, weight loss, increased skin pigmentation (even in areas not exposed to the sun) and loss of appetite, often accompanied by laboratory and physical signs such as low blood pressure, low blood glucose, low sodium, high potassium, and high calcium. Congenital Adrenal Hyperplasia (CAH) is due to an inherited defect in producing cortisol. ACTH may be measured in children suspected of having this condition.

    Findings suggestive of hypopituitarism (usually due to a benign tumour that reduces pituitary gland secretion) include loss of appetite, tiredness, irregular menstrual cycle, hypogonadism (lower levels of sex hormones), decreased sex drive, frequent night time urination, and weight loss. The tumours can also block the nerves controlling vision, causing symptoms such as "tunnel vision" (inability to see things off to the side), loss of vision to some localised areas, and double vision and headaches.

     

  • What does the test result mean?

    ACTH is usually measured if you are found to have low cortisol or have signs or symptoms that suggest adrenal or pituitary disease. Changes in ACTH and cortisol are usually evaluated together, as shown in the table above.

    An increased ACTH concentration in the blood can mean that a patient has Cushing's disease, Addison's disease, or an ectopic ACTH-producing tumour. A decreased ACTH result can suggest an adrenal tumour that is making cortisol or hypopituitarism.

    In some cases, the test results are not clear enough to interpret. Testing the change in ACTH and/or cortisol when certain drugs are given often helps to clarify the picture and allows the doctor to make the right diagnosis. The most commonly used drugs are tetracosactide (trade name Synacthen, a drug form of ACTH) and dexamethasone.

    • Tetracosactide, like ACTH, should normally tell the adrenal glands to make cortisol. If cortisol levels don't rise after tetracosactide is given, this indicates adrenal failure, as can occur in Addison's disease or hypopituitarism.
    • Dexamethasone is a very strong drug that acts like cortisol. In normal people, it should stop ACTH production. By testing the ability of different doses of dexamethasone to stop ACTH production, it is often possible to tell if the patient has Cushing's syndrome and help determine its cause.

    A number of other drugs are sometimes used to help clarify the diagnosis, including insulin, corticotropin releasing hormone (CRH), and metyrapone

  • Is there anything else I should know?

    Some drugs and conditions can cause ACTH levels to rise, including amphetamines, insulin, levodopa, and metoclopramide.

    Drugs that cause ACTH to fall include dexamethasone and other drugs that act like cortisol (including prednisone, hydrocortisone, prednisolone, and methylprednisolone), and megestrol acetate.

    The concentration of ACTH varies greatly at different times of the day, with the highest amount at about 8 am and the lowest about midnight, therefore the sample will normally be collected first thing in the morning.
    Secretion of ACTH may be increased by stress.

  • What is the difference between Cushing's disease and Cushing's syndrome?

    Cushing's syndrome is caused by having too much cortisol. Cushing's disease is when Cushing's syndrome is due to a tumour in the pituitary gland that makes ACTH. Other causes of Cushing's syndrome include adrenal tumours that make cortisol, tumours in other parts of the body (usually the lungs) that make ACTH, and after taking high dose steroids prescribed by your doctor.

  • What is Addison's disease?

    Addison's disease is caused by the destruction of the part of the adrenal gland that makes the hormones cortisol and aldosterone. This is often due to autoimmune disease. TB is a common cause of Addison’s disease in countries where TB is endemic. The lack of cortisol and aldosterone produces symptoms such as weight loss, muscle weakness, tiredness and low blood pressure.

  • My doctor told me that my extra ACTH is not produced in my pituitary gland. What is going on?

    Another way your body can make ACTH is called 'ectopic production'. This means that ACTH is made from tumours elsewhere in the body, usually (but not always) in the lungs. This causes Cushing's syndrome and may alert your doctor to the presence of a tumour.