Meet ACTH: The Tiny Body Messenger That Controls Your Stress and Energy!

Have you ever wondered what happens inside your body when you feel stressed? Your body has a tiny hidden helper that steps in to help you cope. That helper is a messenger chemical known as adrenocorticotropic hormone, or ACTH for short.

Today, we will take a close look at what ACTH does and why it matters to your health. We will explore how your brain and glands work together to keep your body in balance every single day.

What is ACTH?

Put simply, ACTH is a chemical messenger made by your pituitary gland. This hormone plays a big role in how your body responds to physical and mental stress.

When your pituitary gland releases ACTH, it sends a signal to your adrenal glands. That signal tells them to make cortisol, which is your body's main stress hormone. It also tells them to make certain sex hormones called androgens.

Hormones are chemical messengers that coordinate different jobs across your body. These messages travel through your bloodstream to your organs, skin, muscles, and tissues. They tell your body what tasks to do and when to do them.

Your pituitary gland is a tiny pea-sized gland located right at the base of your brain. It sits just below another brain structure called the hypothalamus. This gland is a key part of your endocrine system.

Your pituitary gland has two main parts: the front part and the back part. Your front pituitary lobe is the exact place that makes and releases ACTH into your blood.

What Does ACTH Actually Do?

The main job of ACTH is to stimulate your adrenal glands so they release cortisol. Think of ACTH as a manager that gives orders to your adrenal glands.

Cortisol is an essential hormone that your body truly cannot live without. It affects nearly every single organ and tissue inside your body.

Cortisol is widely known as the stress hormone. However, it also has many other vital jobs to do every day.

Here are some of the most important things cortisol does for you:

• It manages how your body reacts to mental and physical stress.
• It controls your metabolism by deciding how your body uses fats, proteins, and carbohydrates.
• It helps reduce inflammation, which is swelling and redness in your tissues.
• It helps regulate your blood pressure to keep you steady.
• It helps keep your blood sugar levels within a healthy range.
• It helps support your natural sleep and wake cycle.

ACTH also does more than just control cortisol. It prompts your adrenal glands to release androgens as well.

It also helps trigger chemicals that make your adrenal glands ready to produce other fast-acting hormones like adrenaline and noradrenaline when needed.

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How is ACTH Controlled?

Your body controls your ACTH levels using a clever feedback system. This system involves your hypothalamus, your pituitary gland, your adrenal glands, and several hormones.

Doctors call this entire connected system the hypothalamic-pituitary-adrenal axis, or HPA axis for short. While the name sounds complex, the process itself is very straightforward.

Your pituitary gland connects to your hypothalamus through a tiny stalk filled with blood vessels and nerves. This stalk lets your hypothalamus talk to your pituitary gland and tell it when to release hormones.

Your hypothalamus is a part of your brain that controls vital things. It manages your blood pressure, heart rate, body temperature, and digestion.

Your adrenal glands are two small, triangle-shaped glands that sit right on top of your kidneys.

Here is how the feedback system works step by step:

• When your body has low cortisol levels, your hypothalamus releases a chemical called corticotropin-releasing hormone, or CRH.
• This CRH stimulates your front pituitary lobe to release ACTH into your bloodstream.
• The ACTH then travels to your adrenal glands, specifically the outer layer called the adrenal cortex, to trigger cortisol and androgen release.
• When your cortisol levels go up, it sends a signal back to your hypothalamus to slow down or stop making CRH.
• This cycle repeats continuously, acting just like an automatic on and off switch for your hormones.

When you experience stress, your body ramps up this process. Your brain increases ACTH production so your body gets a quick boost of cortisol to help you cope.

However, if something goes wrong with your hypothalamus, pituitary gland, or adrenal glands, this delicate hormone balance can easily get disrupted.

How Do Doctors Test ACTH?

Doctors check your ACTH level using a routine blood test. A doctor takes a small sample of blood from a vein in your arm.

Most of the time, doctors order an ACTH blood test along with a cortisol blood test. Doing both tests helps them check for problems in your pituitary gland or your adrenal glands.

Your doctor may also perform a special test called an ACTH stimulation test. This test checks how well your adrenal glands respond when given a dose of synthetic ACTH.

Results from these tests help your medical team figure out if your symptoms stem from a pituitary issue or an adrenal gland issue.

What is a Normal ACTH Level?

Just like cortisol, your blood ACTH level peaks early in the morning right after you wake up. It gradually drops throughout the day and reaches its lowest point around midnight.

If you work night shifts or sleep during odd hours of the day, your natural daily pattern may shift.

Because of this daily rhythm, doctors usually prefer to draw blood tests for ACTH during morning hours. Generally speaking, normal ACTH levels measured between 7:00 AM and 10:00 AM range from 7.2 to 63.3 picograms per milliliter.

Keep in mind that normal laboratory ranges can vary from one lab to another. Your doctor will review your specific lab results and look at your symptoms to decide if you need further testing.

What Happens When ACTH is High?

If your body has high ACTH levels, your cortisol levels are usually high as well. Because cortisol affects many parts of your body, you will often notice the side effects of high cortisol rather than high ACTH.

Sometimes, your adrenal glands fail to make enough cortisol. When this happens, your body tries to compensate by making more ACTH.

High ACTH levels can happen for several different medical reasons:

• Cushing Disease: This is the most common cause of high ACTH. It happens when a noncancerous tumor grows on the pituitary gland and makes too much ACTH, which then drives up cortisol. Note that Cushing disease is just one specific cause of a broader condition called Cushing syndrome.
• Ectopic ACTH Tumor: In rare cases, a tumor outside the pituitary gland starts making ACTH. These tumors can sometimes form in the lungs as noncancerous carcinoid tumors, in the pancreas as islet cell tumors, in the thyroid gland as medullary carcinoma, or in the thymus gland.
• Primary Adrenal Insufficiency: This happens when your adrenal glands suffer damage and cannot make enough cortisol. Addison disease is a well-known example of primary adrenal insufficiency. Because your adrenal glands cannot make cortisol, your pituitary gland pumps out extra ACTH in a vain attempt to stimulate them.

What Happens When ACTH is Low?

If your pituitary gland has a problem, your ACTH level may drop, which usually leads to low cortisol levels. On the other hand, if an adrenal tumor causes high cortisol levels, that high cortisol can suppress your ACTH production.

Low ACTH levels can happen for a couple of key reasons:

• Cushing Syndrome: If an adrenal gland tumor makes too much cortisol, or if you take high-dose corticosteroid medicines for a long time, your ACTH levels drop. This happens because high cortisol tells your pituitary gland to stop releasing ACTH.
• Hypopituitarism: This is a rare condition where your pituitary gland fails to make one, several, or all of its hormones. ACTH can be one of the hormones that drops. Any damage to your pituitary gland, such as pressure from a growth, surgery, or radiation therapy, can cause hypopituitarism.

You can now see why ACTH is so important for keeping your cortisol levels balanced. If you notice signs of abnormal cortisol levels—such as unexpected weight gain or loss, high blood pressure, or extreme muscle weakness—you should schedule an appointment with your doctor right away.

Your doctor can run simple blood tests to check your ACTH and cortisol levels. These tests help find out if your symptoms come from an issue with your adrenal glands or your pituitary gland.

What Should We Remember?

ACTH is a vital hormone made by your pituitary gland that helps your body manage physical and mental stress.

It tells your adrenal glands to produce cortisol, which is your body's main stress hormone.

Cortisol helps control your metabolism, blood pressure, blood sugar, and energy levels.

ACTH levels are controlled by a feedback loop involving your hypothalamus, pituitary gland, and adrenal glands.

Abnormal ACTH levels can lead to health conditions like Cushing disease or Addison disease.

If you have ongoing symptoms, speak with a doctor to get professional medical advice and testing.

Hormone Comparison at a Glance.