ACTH is a hormone produced in the anterior (front) pituitary gland in the brain. The function of ACTH in the body is to regulate levels of the steroid hormone cortisol, released from the adrenal gland.
ACTH is also known as adrenocorticotropic hormone, serum adrenocorticotropic hormone, highly-sensitive ACTH, corticotropin, and cosyntropin (a drug form of ACTH).
An ACTH test measures the levels of both ACTH and cortisol in the blood and helps physicians detect diseases that are associated with too much or too little cortisol in the body. Possible causes of these diseases include:
- adrenal or pituitary malfunction
- a pituitary tumor
- a adrenal tumor
- a lung tumor
Before your test, your doctor may advise you not to take any steroid drugs, as these can affect the accuracy of the results. The test is usually done first thing in the morning. Like other hormones, ACTH is at its highest level upon waking. Because of this, your test will likely be scheduled for as soon as the clinic opens on that particular day.
Testing the level of ACTH is done using a blood sample. A blood sample is taken by drawing blood from a vein, usually from the inside of the elbow. The site is first cleaned with a germ-killing antiseptic. Then an elastic band is wrapped around your arm, causing the vein to swell with blood.
The healthcare provider gently inserts a needle syringe into your vein, and blood collects in the syringe tube. When the tube is full, the needle is removed. The elastic band is then removed, and the puncture site is covered with sterile gauze to stop the bleeding.
When a patient has symptoms of too much or too little cortisol, their physician may order an ACTH blood test. These symptoms can vary widely from person to person and are often a sign of additional health problems.
People with high cortisol levels may have:
- a rounded face
- fragile, thin skin
- purple lines on the abdomen
- weak muscles
- increased body hair
- high blood pressure
- low potassium levels
- high bicarbonate level
- high glucose levels
Patients with of low cortisol may have:
- weak muscles
- weight loss
- increased skin pigmentation in areas not exposed to the sun
- loss of appetite
- low blood pressure
- low blood glucose
- low sodium
- high potassium
- high calcium levels
Normal values of ACTH are 9 to 52 pg/mL (picograms per milliliter). Normal value ranges may vary slightly with different laboratories. Your doctor will explain your test results to you.
High levels of ACTH may be a sign of:
- Addison’s disease
- adrenal hyperplasia
- Cushing’s disease
- ectopic tumor which produces ACTH
- adrenoleukodystrophy (very rare)
- Nelson’s syndrome (very rare)
Low levels of ACTH may be a sign of:
- adrenal tumor
- exogenous Cushing syndrome
Taking steroid medications can cause low levels of ACTH, so be sure to tell your doctor if you are on any steroids.
Blood tests are normally well-tolerated. Some people have smaller or larger veins, which may make taking a blood sample more difficult. However, risks associated with blood tests like the ACTH hormone test are rare.
Uncommon risks of having blood drawn include:
- excessive bleeding
- feeling light headed or fainting
- hematoma (blood pooling under the skin)
- infection at the site
Diagnosis of ACTH diseases can be highly complex. Certain drugs increase or decrease the level of cortisol and ACTH in the blood. These drugs can be used to find the precise cause of any underlying condition and help the doctor develop the best course of treatment. Treatment usually involves prescription medications or even surgery in the case of certain tumors.