Test Quick Guide

Adrenocorticotropic hormone (ACTH) stimulates the production of cortisol. A steroid hormone made by the adrenal glands, cortisol is important for regulating glucose, protein, and lipid metabolism, suppressing the immune system’s response, and helping maintain blood pressure.

ACTH blood tests measure the amount of the hormone in the blood and are used in conjunction with cortisol tests to help detect conditions associated with abnormal cortisol levels.

About the Test

Purpose of the test

ACTH blood tests are used, usually in conjunction with cortisol tests, to help detect, diagnose, and monitor conditions associated with excessive or deficient cortisol in the body. These conditions include:

  • Cushing’s disease: excess cortisol due to an ACTH-producing tumor in the pituitary gland (usually a benign tumor)
  • Cushing’s syndrome: the symptoms and signs associated with excess cortisol; in addition to Cushing’s disease, Cushing’s syndrome may be due to an adrenal tumor, adrenal hyperplasia, the use of steroid medications, or an ACTH-producing tumor located outside the pituitary (ectopic), such as in the lungs.
  • Addison’s disease (primary adrenal insufficiency): decreased cortisol production due to adrenal gland damage
  • Secondary adrenal insufficiency: decreased cortisol production because of pituitary dysfunction
  • Hypopituitarism: pituitary dysfunction or damage that leads to decreased (or no) hormone production by the pituitary, including ACTH production

Measuring both ACTH and cortisol can help to differentiate among some of these conditions because the level of ACTH normally changes in the opposite direction to the level of cortisol.

If abnormal levels are detected, a health care practitioner will do additional testing to help confirm the findings and help determine the cause.

What does the test measure?

ACTH is produced by the pituitary gland. Located below the brain in the center of the head, the pituitary gland is part of the endocrine system, a network of glands that work together to produce hormones that act on organs, tissues, and other glands to regulate systems throughout the body.

Normally, ACTH levels increase when cortisol is low and fall when it is high. In response to a drop in the blood cortisol level, the hypothalamus produces corticotropin-releasing hormone (CRH). This stimulates the production of ACTH by the pituitary, which in turn stimulates the production of cortisol by the adrenal glands, small organs located at the top of each kidney.

The hypothalamus, pituitary, and adrenal glands must function properly to make the appropriate amounts of cortisol.

Conditions that affect the hypothalamus, pituitary, or adrenal glands can interfere with regulating ACTH and cortisol production, increasing or decreasing how much of the hormones the glands produce. This can cause signs and symptoms associated with an excess or deficiency of cortisol.

Conditions that affect ACTH include Cushing’s disease, adrenal insufficiency (Addison’s disease), and hypopituitarism. Some tumors found outside of the pituitary in locations such as the lungs can also increase cortisol concentrations by producing ACTH.

When should I get this test?

An ACTH test may be ordered after a cortisol test reveals abnormal results and when someone has signs or symptoms associated with excess or deficient cortisol.

Too much cortisol can cause symptoms that include:

  • Obesity, with majority of the weight on the trunk of the body and not the arms and legs
  • Fat collection between the shoulders
  • Rounded, red face
  • Fragile and thin skin
  • Purple lines on the abdomen
  • Muscle weakness
  • Acne
  • Skin infections
  • Increased body hair
  • Fatigue

These are often accompanied by findings such as high blood pressure, low potassium, high bicarbonate, high glucose levels, and sometimes diabetes.

If you have insufficient cortisol production you may exhibit symptoms such as:

  • Muscle weakness
  • Fatigue
  • Weight loss
  • Increased skin pigmentation, even in areas not exposed to the sun
  • Loss of appetite
  • Diarrhea, nausea and vomiting
  • Dizziness
  • Salt cravings

These are often accompanied by findings such as low blood pressure, low blood glucose, low sodium, high potassium, and high calcium.

Symptoms suggestive of hypopituitarism typically include several of the following:

  • Loss of appetite
  • Fatigue
  • Irregular menstrual cycle
  • Dysfunction of sex organs (hypogonadism)
  • Decreased sex drive
  • Frequent nighttime urination
  • Unexplained weight loss
  • Hot flashes
  • Cold sensitivity

When the condition is due to a pituitary tumor (usually benign), the affected person may also have symptoms associated with the compression of nearby cells and nerves. For example, the tumor can cause a change in a pattern of headaches. It can also affect the nerves controlling vision, causing symptoms such as “tunnel vision” (inability to see things off to the side), loss of vision to some localized areas, or double vision.

Finding an Adrenocorticotropic Hormone (ACTH) Test

How can I get an adrenocorticotropic hormone (ACTH) test?

ACTH tests are commonly ordered by a health care professional to be performed in a laboratory setting. You can also order an ACTH test online without a doctor’s prescription, but you’ll still need to visit a lab to have your sample taken.

Can I take the test at home?

While you can purchase an online ACTH test from home, you can’t perform the test yourself at home. The test requires you to take a blood sample at a lab.

If you buy an at-home test, it’s still best to consult with a medical professional about your results.

How much does the test cost?

The cost of ACTH testing varies based on where the test is performed and your insurance plan. Your insurance company may pay for some or all of these costs if your doctor prescribes your test. For the most definitive information about likely costs, talk with your doctor’s office and medical insurance company.

Taking an Adrenocorticotropic Hormone (ACTH) Test

During an ACTH test, a blood sample will be drawn from a vein in your arm by a medical professional or lab technician.

Before the test

Generally, no preparation is needed before an ACTH test; however, your health care practitioner may request that you fast overnight before testing. Blood is typically drawn at about 8 a.m.

During the test

During an ACTH test, a blood sample will be taken from a vein in your arm. This is usually done by tying an elastic tourniquet around your upper arm to increase blood flow and make it easier to access the vein.

The technician will then use an antiseptic wipe to clean the skin around the vein before inserting the needle. Once the blood vial has been filled, the needle will be withdrawn.

This process usually only lasts a few minutes. There may be some minor pain during the procedure, but most people feel little more than a brief sting when the needle is inserted.

After the test

After the test, a cotton swab will be placed over the puncture site and a bandage wrapped around your arm to keep it in place. You can resume your normal activities once the test is completed, but avoiding heavy lifting for at least 24 hours may be best.

Adrenocorticotropic Hormone (ACTH) Test Results

Receiving test results

In most cases, ACTH test results are available within a few business days. Test results can be sent by mail or accessible through online health portals. You may also receive a call or email from your doctor to either review your results or schedule a follow-up appointment.

Interpreting test results

In many cases, interpreting the results can be complex. Levels of both ACTH and cortisol vary throughout the day. Normally, ACTH will be at its highest level in the morning and lowest at night. It will stimulate cortisol production, which follows the same daily pattern but rises after ACTH and falls to its lowest level late in the evening.

Conditions that affect the production of ACTH and cortisol often disrupt this diurnal variation.

Results of ACTH and cortisol tests are often evaluated together. The table below indicates the common patterns of ACTH and cortisol seen with different diseases involving the adrenal and pituitary glands.

An increased ACTH result can mean that you have Cushing’s disease, Addison’s disease, overactive, tumor-forming endocrine glands (multiple endocrine neoplasia), or ectopic ACTH-producing tumors.

A decreased ACTH result can be due to an adrenal tumor, steroid medication, or hypopituitarism.

It is impossible to distinguish Cushing’s disease and ectopic ACTH from cortisol and ACTH measurement alone. Various other tests are often used to assist health care practitioners in making this distinction. Testing the change in the level of cortisol when certain drugs are given to stimulate or suppress hormone production often helps the health care practitioner make the right diagnosis.

Questions you may want to ask your doctor about your test results include:

  • Were any other measurements taken along with my ACTH levels? If so, were they normal or abnormal?
  • If my ACTH is abnormal, what is the most likely cause?
  • Are there any follow-up tests you recommend?
  • Should I make changes to my diet or lifestyle?


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