Understanding the ACTH test (Adrenocorticotropic Hormone)

ACTH test assesses the adrenal cortex’s ability to respond to adrenocorticotropic hormone (ACTH) by producing cortisol as needed. ACTH is a pituitary gland hormone responsible for stimulating the adrenal glands.

What is the ACTH test?

This analysis is ordered to determine the level of adrenocorticotropic hormone (ACTH)  in the blood. ACTH is a hormone secreted by the pituitary gland; a small gland located at the base of the brain.

ACTH regulates the production of another hormone called cortisol; which is produced by the adrenal glands, which are 2 small glands found above the kidneys.

Cortisol is essential in helping you to:

• Respond to stress.
• Fight infection.
• Regulate Blood glucose.
• Maintain blood pressure.
• Regulate metabolism.

An ACTH testing assists your doctor in diagnosing adrenal and pituitary problems related to too much or too little cortisol in the body, such as:

1. Pituitary or adrenal dysfunction.
2. Hypoadrenocorticism.
3. Cushing’s syndrome.
4. Primary adrenal insufficiency (Addison’s disease).
5. Secondary adrenal insufficiency.
6. Adrenal tumor.
7. Pituitary tumor.
8. Lung tumor.

Brief Description for ACTH test

“Related: What Is Urobilinogen Test In Urine and Why It’s Important?“

Why the ACTH test is performed?

If you have symptoms of too much or too little cortisol, your doctor may order an ACTH blood test. These symptoms can vary greatly from person to another, and are frequently a sign of health cases.

In case of too much cortisol

Symptoms of too much cortisol include:

• Obesity
• A rounded face
• Thin skin
• Stretch marks (lines) on the abdomen, thighs, and/or breasts that are pink or purple.
• Muscle weakness.
• An increase in body hair.
• High blood pressure
• Potassium deficiency
• Diabetes
• High bicarbonate level
• Fat accumulation in the shoulders
• Fatigue
• Acne

In case of too little cortisol

Symptoms of low cortisol include:

• Fatigue
• weak muscles
• increased skin pigmentation in non-sun-exposed areas
• loss of appetite
• Too low blood pressure
• low levels of blood glucose
• sodium deficiency
• excessive potassium levels
• calcium deficiency
• Loss of weight
• Vomiting and nausea
• Diarrhea
• Pain in the abdomen
• Dizziness
• Craving for salt

You may also need this test if you have symptoms of hypopituitarism, which show symptoms depending on the severity of the disease such as:

• Appetite loss
• Women’s infertility and irregular menstrual cycles
• Male body and facial hair loss
• Men and women have a lower sex drives.
• Cold sensitivity
• excessive urine more than usual.
• Fatigue

What happens during the ACTH test?

A blood sample is used to test ACTH levels. Blood is drawn from a vein, usually, the inside of the elbow, to obtain a blood sample.

The following steps are involved in blood sampling:

• The healthcare provider first cleans the site using an antiseptic.
• The elastic band will then be wrapped around your arm. As a result, the vein swells with blood.
• Gently a needle syringe will be inserted into your vein (iv) and draw a sufficient amount of blood.
• The needle is removed when the tube is full.
• To stop the bleeding, the elastic band is removed and the puncture site is covered with sterile gauze.
• When the needle goes in or out, you may feel a slight sting. This usually takes under five minutes.

Your doctor will most likely schedule your test for very early in the morning when ACTH levels are at their peak.

Before your test, your doctor will advise you not to take any steroid medications. These can have an impact on the accuracy of the results.

The Risks of an ACTH Test

Blood tests are usually tolerated well. Because some patients have large or small veins, which may make getting a blood sample more difficult. However, the risks associated with blood tests such as the ACTH hormone test are relatively rare.

The following are unordinary risks of having blood drawn:

• Excessive bleeding
• Feeling dizzy or fainting
• Hematoma (blood accumulation beneath the skin)
• infection at the location

Results Interpretations

ACTH levels in the normal range are 7.2−63.3 pg/mL.

High level of ACTH

In case of ACTH results are higher than normal may indicate:

• The adrenal glands do not produce enough hormones (congenital adrenal hyperplasia).
• Cortisol production by the adrenal glands is insufficient (Addison disease).
• One or more endocrine glands are overactive or have developed a tumour (multiple endocrine neoplasia type I)
• The pituitary gland produces too much ACTH (Cushing disease), which is usually caused by a non-cancerous pituitary tumour.
• A rare type of tumor (lung, thyroid, or pancreas) that produces excessive ACTH (ectopic Cushing syndrome).

Low level of ACTH

A lower-than-normal ACTH level may indicate:

• ACTH production is suppressed by glucocorticoid medications (most common).
• A normal reaction to the low-dose dexamethasone suppression test.
• The pituitary gland produces insufficient hormones, such as ACTH (hypopituitarism).
• Adrenal gland tumor that produces excessive cortisol.

Additional information

Some drugs and conditions, such as insulin, amphetamines, metoclopramide, and levodopa can cause an increase in ACTH levels.

Dexamethasone and other cortisol-like drugs (including hydrocortisone, prednisone, prednisolone, and methylprednisolone) cause ACTH to fall, as does the progestational drug megestrol acetate, which is used in various cancer treatments.

Stress can significantly increase ACTH secretion, particularly during childbirth or psychotic illness.

While ACTH is used to diagnose primary adrenal insufficiency (Addison disease), the ACTH stimulation test is the preferred diagnostic test.

ACTH diseases can be difficult to diagnose.  Before diagnosis, your doctor may need to confirm the results by ordering additional lab tests and performing a physical screening.