ACTH Stimulation Test, What’s It For?

A doctor or healthcare provider may recommend an adrenocorticotropic hormone (ACTH) simulation test if an individual is suspected of having improperly functioning adrenal glands.

ACTH Stimulation Test

What’s an ACTH stimulation test?

A doctor or healthcare provider may recommend an adrenocorticotropic hormone (ACTH) stimulation test if an individual is suspected of having improperly functioning adrenal glands.

The ACTH is one of the many types of hormones produced by the pituitary gland. It triggers the adrenal glands to release adrenaline and cortisol. These two hormones are released to support the immune system and help the body respond healthily to stress.

Many bodily systems are affected by cortisol. This steroid hormone affects the nervous system, immune system, and circulatory system. It also impacts the metabolism of the bones, protein, fats, and carbohydrates.

Also called epinephrine, adrenaline is involved in maintaining normal circulatory function and nervous system. Together with norepinephrine, they are the protective fight-or-flight response to different stressful situations.

An injection of cosyntropin is part of an ACTH test. A blood sample will be drawn prior to the injection and another sample thereafter. These two blood samples will then be used to gauge cortisol levels in the blood.

The ACTH stimulation test aims to gauge the adrenal glands’ reaction to the blood’s ACTH. This is different from the simpler ACTH test, which only measures the blood’s ACTH levels.


The Purpose of an ACTH Stimulation Test

The ACTH stimulation test is basically performed to detect Addison’s disease, a condition marked by adrenal insufficiency. It can also be used to spot if an individual is suffering from hypopituitarism, which is causing the pituitary gland not to work correctly. A secondary adrenal insufficiency may also be caused alternately by deficient cortisol.

The ACTH blood level and the ACTH test can be used side by side to determine if the adrenal gland is suffering from excessive cortisol secretion. This is what usually happens in patients with Cushing’s syndrome.

The doctor may recommend an ACTH stimulation test if the patient is suffering from irritability, depression and mood changes. Sometimes, there is also a skin discoloration or darkening. The test can also be helpful for individuals who are experiencing fatigue, joint and muscle pains, and muscle weakness. Appetite loss, low blood pressure, and unexplained weight loss can also prompt the doctor to ask you to take the test.

Excessive cortisol secretion is also marked by low sex drive in males, irregular menstruation in females as well as the increased development of hair in the body and face. Other symptoms and signs include obesity, round face, and acne.

An ACTH stimulation test can help the doctor or healthcare provider identify if these signs and symptoms are caused by malfunctioning adrenal glands.


Slight Risks of an ACTH Stimulation Test

When blood is drawn from patients during an ACTH stimulation test, there are certain risks involved. They may experience vein inflammation at the area where the blood is drawn. There is also a risk of hematoma, fainting, and too much bleeding. Sometimes, infection and lightheadedness are also possible.

Inserting the needle will cause the patients to feel moderate to mild pain depending on their tolerance. Once the needle is removed, throbbing pain may also be felt in the puncture location. When the needle is removed, there can be mild bleeding in the area to be followed by a small bruise. Serious long-lasting effects are not expected to individuals who take an ACTH stimulation test.  


Ways to Prepare for an ACTH Stimulation Test

Preparations may vary from one patient to the next. Be sure to closely follow the instructions of your doctor or healthcare provider. A patient may be required to fast for 8 hours prior to testing.

In addition, some medications should not be taken 24 hours before taking an ACTH stimulation test. The list of common drugs which may affect the levels of cortisol includes birth control pills, male hormones, and steroid medications. The same is also true for the antiseizure drug phenytoin, lithium, amphetamines, and estrogen.


How to Perform an ACTH Stimulation Test

Once you arrive for an ACTH stimulation test, a blood sample will be drawn by the doctor or healthcare provider. The purpose of this is to gauge the cortisol levels in the blood. This will serve as a baseline to be compared later to the second blood test results.

Cosyntropin will be injected into the patient. The hormone will prompt the production of cortisol by the adrenal glands. It will take approximately one hour for the body to react to the injected cosyntropin.

Once the first hour has ended, the second blood sample will be taken by the doctor or healthcare provider. This will represent the levels of cortisol upon the body’s reaction to the injection. The results of the ACTH stimulation test will normally arrive after a week or two. The cortisol levels will be measured in the two blood samples.


Interpreting the Results of an ACTH Stimulation Test

If the adrenal glands are properly functioning, the cortisol levels in the blood should increase following the ACTH stimulation. The results of the test may slightly vary. If there are concerns, communicate them clearly with the doctor or healthcare provider.

Things are not normal if the levels of cortisol in the blood are lower than the accepted range. These findings may indicate a number of conditions including hypopituitarism, Addison’s disease or acute adrenal crisis.

If the levels of cortisol in the blood are over the anticipated range after the ACTH stimulation, this is a sign of Cushing’s syndrome. This kind of diagnosis can be confirmed by further testing. Be sure to talk with the doctor or healthcare provider on how to best proceed once the testing process becomes complicated.


Additional Information

Addison’s disease is a condition that may be potentially life-threatening. After confirming the diagnosis, it is very important to start treatment right away.

An ACTH stimulation test is regarded as a safer and easier alternative to an insulin tolerance test, which is the gold standard test for diagnosing Addison’s disease.

Other names for the ACTH stimulation test are the Synacthen test, tetracosactide, and cosyntropin. This medical test is normally endorsed and interpreted by an endocrinologist. It aims to evaluate the stress response of the adrenal glands.  

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