Serum Adrenocorticotropic Hormone Test (ACTH)

Last updated: February 8, 2026 Medically reviewed by: RxHarun Orthopedic Specialist Doctor Reading time: 6 min read

Serum adrenocorticotropic hormone; Adrenocorticotropic hormone; Highly-sensitive ACTH

The ACTH test measures the level of adrenocorticotropic hormone (ACTH) in the blood. ACTH is a hormone released from the pituitary gland in the brain

This test measures the level of adrenocorticotropic hormone (ACTH) in the blood. ACTH is a hormone made by the pituitary gland, a small gland at the base of the brain. ACTH controls the production of another hormone called cortisol.

How the Test is Performed

A blood sample is needed.

How to Prepare for the Test

Your doctor will likely ask you to have the test done early in the morning. This is important because cortisol level varies throughout the day.

You may also be told to stop taking medicines that can affect the test results. These medicines include glucocorticoids such as prednisone, hydrocortisone, or dexamethasone.

How the Test will Feel

When the needle is inserted to draw blood, some people feel moderate pain. Others feel only a prick or stinging. Afterward, there may be some throbbing or slight bruising. This soon goes away.

Why the Test is Performed

The main function of ACTH is to regulate the steroid hormone cortisol. Cortisol is released by the adrenal gland . It regulates blood pressure and blood sugar.

This test can help find the causes of certain hormone problems.

Normal Results

Normal values for a blood sample taken early in the morning are 9 to 52 pg/mL.

Normal value ranges may vary slightly among different laboratories. Some labs use different measurements or may test different specimens. Talk to your doctor about the meaning of your specific test results.

What Abnormal Results Mean

A higher-than-normal level of ACTH may indicate:

Adrenal glands not producing enough cortisol ( Addison disease )
Adrenal glands not producing enough hormones ( congenital adrenal hyperplasia )
One or more of the endocrine glands are overactive or have formed a tumor ( multiple endocrine neoplasia type I )
The pituitary is making too much ACTH ( Cushing disease ), which is usually caused by a non-cancerous tumor of the pituitary gland
Rare type of tumor (lung, thyroid, or pancreas) making too much ACTH ( ectopic Cushing syndrome )

A lower-than-normal level of ACTH may indicate:

The pituitary gland not produce enough hormones, such as ACTH ( hypopituitarism )
Tumor of the adrenal gland that produces too much cortisol
Glucocorticoid medicines are suppressing ACTH production

Risks

Veins and arteries vary in size from one person to another and from one side of the body to the other. Obtaining a blood sample from some people may be more difficult than from others.

Other risks associated with having blood drawn are slight but may include:

Excessive bleeding
Fainting or feeling lightheaded
Hematoma (blood accumulating under the skin)
Infection (a slight risk any time the skin is broken)

FAQ

What is a normal ACTH level?

Between 10 and 60 pg/mL
Normal values — Plasma corticotropin (ACTH) concentrations are usually between 10 and 60 pg/mL (2.2 and 13.3 pmol/L) at 8 AM.

What does a low ACTH level mean?

A decline in the concentration of ACTH in the blood leads to a reduction in the secretion of adrenal hormones, resulting in adrenal insufficiency (hypoadrenalism). Adrenal insufficiency leads to weight loss, lack of appetite (anorexia), weakness, nausea, vomiting, and low blood pressure (hypotension).

Why would a doctor order an ACTH stimulation test?

The ACTH stimulation test is used to diagnose adrenal insufficiency, a condition known as Addison’s disease. It is also used to determine if the pituitary gland is not working properly due to hypopituitarism.

What happens if ACTH is high?

An increased ACTH result can mean that a person has Cushing disease, Addison disease, overactive, tumor-forming endocrine glands (multiple endocrine neoplasias), or ectopic ACTH-producing tumors. A decreased ACTH result can be due to an adrenal tumor, steroid medication, or hypopituitarism.

When should the ACTH test be done?

The test is usually done first thing in the morning. ACTH levels are highest when you’ve just woken up. Your doctor will likely schedule your test for very early in the morning. ACTH levels are tested using a blood sample.

What is the function of ACTH?

Adrenocorticotropic hormone (ACTH) is produced by the pituitary gland. Its key function is to stimulate the production and release of cortisol from the cortex (outer part) of the adrenal gland.

How do you feel during the ACTH stimulation test?

When the needle is inserted to draw blood, some people feel moderate pain, while others feel only a prick or stinging sensation. Afterward, there may be some throbbing. Why the test is performed: This test is helpful in determining if the adrenal and pituitary glands are normal.

Is ACTH high or low in Cushing’s?

If these tests show high cortisol levels, the doctor will then measure the ACTH level in the blood. In Cushing’s disease, the cortisol levels are high, and the ACTH levels are normal or high. If these results are seen, the doctor will schedule an MRI of the pituitary gland to pinpoint the location of any tumors.

What type of hormone is adrenocorticotropic hormone?

peptide hormone
Adrenocorticotropic hormone (corticotropin; ACTH) is a 39-amino-acid peptide hormone produced by cells of the anterior pituitary gland and carried by the peripheral circulation to its effector organ, the adrenal cortex, where it stimulates the synthesis and secretion of glucocorticoids and, to a more modest extent

Is fasting required for the ACTH test?

ACTH Test Preparation
If you take steroids, you’ll need to stop for up to 48 hours before the test. Steroids can affect the test results. Your doctor might ask you to limit your carbohydrates in the 48 hours leading up to the test as well.

Can you drink water before the ACTH test?

You will need to fast (no food or drinks other than water) after 10:00 pm the night before your test. Please DO drink water the morning of the test. You can bring a snack to eat once the test is completed. Your doctor may also want you to take dexamethasone at 11:00 pm the night before the test.

What stimulates ACTH secretion?

CRH stimulates the anterior pituitary to release ACTH. ACTH acts on the adrenal cortex to release cortisol and androgens. The increase in cortisol provides a negative feedback system to decrease the amount of CRH released from the hypothalamus.

What causes low ACTH and cortisol?

It occurs when the pituitary gland is unable to make enough adrenocorticotropin hormone (ACTH). ACTH sends a signal to the adrenal glands and stimulates them to make cortisol. If the pituitary gland does not make enough ACTH, the body will have low levels of cortisol.

What causes low ACTH?

Isolated ACTH deficiency is caused by damage to the ACTH-producing cells of the pituitary gland and can lead to secondary adrenocortical insufficiency.

What are the symptoms of low ACTH?

Symptoms include fatigue, weakness, weight loss, nausea, vomiting, and diarrhea, but there is usually less hypovolemia. Diagnosis is clinical and by laboratory findings, including low plasma ACTH with low plasma cortisol.

How does cortisol affect ACTH?

The adrenal cortex secretes cortisol in response to ACTH. When plasma cortisol increases, it suppresses the release of CRH and ACTH, which, in turn, leads to a lowering of the cortisol level.

How do you treat low ACTH?

ACTH deficiency. ACTH deficiency can be treated with either hydrocortisone or prednisolone, which is a synthetic corticosteroid drug [³]. In patients with hypopituitarism whose aldosterone levels are approximately normal, there is no need to replace mineralocorticoids.

Frequently Asked Questions

Is this article a replacement for a doctor?

No. It is educational content only. Patients should consult a qualified clinician for diagnosis and treatment.

When should I seek urgent care?

Seek urgent care for severe symptoms, rapidly worsening condition, breathing difficulty, severe pain, neurological changes, or any emergency warning sign.

References

Add references, clinical guidelines, textbooks, journal articles, or trusted medical sources here. You can edit this area later with a custom field named _rx_references.

Written by Dr. Harun Ar Rashid, MD - Arthritis, Bones, Joints Pain, Trauma, and Internal Medicine Specialist

Dr. Md. Harun Ar Rashid, MPH, MD, PhD, is a highly respected medical specialist celebrated for his exceptional clinical expertise and unwavering commitment to patient care. With advanced qualifications including MPH, MD, and PhD, he integrates cutting-edge research with a compassionate approach to medicine, ensuring that every patient receives personalized and effective treatment. His extensive training and hands-on experience enable him to diagnose complex conditions accurately and develop innovative treatment strategies tailored to individual needs. In addition to his clinical practice, Dr. Harun Ar Rashid is dedicated to medical education and research, writing and inventory creative thinking, innovative idea, critical care managementing make in his community to outreach, often participating in initiatives that promote health awareness and advance medical knowledge. His career is a testament to the high standards represented by his credentials, and he continues to contribute significantly to his field, driving improvements in both patient outcomes and healthcare practices. Born and educated in Bangladesh, Dr. Rashid earned his BPT from the University of Dhaka before pursuing postgraduate training internationally. He completed his MD in Internal Medicine at King’s College London, where he developed a special interest in inflammatory arthritis and metabolic bone disease. He then undertook a PhD in Orthopedic Science at the University of Oxford, conducting pioneering research on cytokine signaling pathways in rheumatoid arthritis. Following his doctoral studies, Dr. Rashid returned to clinical work with a fellowship in interventional pain management at the Rx University School of Medicine, refining his skills in image-guided joint injections and minimally invasive pain-relief techniques.