ACTH Stimulation Test
What is the ACTH stimulation test?
Different glands exist in the body. Glands are organs that secrete substances required in different processes in the body. One such gland is the pituitary gland. It is found in the brain, just at its base. It looks like a pea in size. It produces ACTH (adrenocorticotropic hormone) amongst several other hormones.
ACTH primarily acts on the adrenal glands in order to cause cortisol and adrenaline to be released. The adrenal glands are situated just on top of the kidneys. These two hormones can be called stress hormones because they help your body to positively respond to stress. They also support your immune system.
Cortisol is termed a steroid hormone. It acts on your circulatory system, immune system, nervous system, and bone, carbohydrate, protein, and fat metabolisms.
Adrenaline, which can as well be called epinephrine, oversees the maintenance of the circulatory and nervous systems.
Adrenaline works hand-in-hand with norepinephrine to help you respond to stressful situations.
Your doctor may decide to carry out an ACTH (cosyntropin) test on you if he is not sure of the state of your adrenal glands. To do this diagnosis, you will be injected with synthetic ACTH referred to as cosyntropin. Before this is done, your blood will be taken to know the cortisol concentration. After receiving the injection, another blood will be drawn from you to assess its concentration again.
The ACTH stimulation test, in reality, checks the responsiveness of your adrenal glands to the release of ACTH by directly assessing your cortisol level in the blood. This test is entirely different from an ACTH test in that the ACTH test measures your ACTH blood levels.
Why you might need the test
This test is targeted at diagnosing any adrenal incompetence especially Addison’s disease.
It is also useful in the determination of the functionality of the pituitary gland as a result of hypopituitarism. Insufficient cortisol could mean secondary adrenal insufficiency is lurking around.
This test can be used together with an ACTH test to ascertain the presence of Cushing syndrome. In Cushing syndrome, cortisol is overproduced by the adrenal gland.
If you are experiencing in a progressive manner, any of the following symptoms, an ACTH stimulation test may be required.
- Weight loss with no specific explanation
- Mood swings
- Unexplained irritation
- Weak muscles
- Inability to eat
- Low blood pressure
- Painful muscles and joints
- Extreme tiredness
- Skin discoloration – skin becomes darkened
Excessive cortisol secretion is signaled by any of the following; trunk obesity, acne, round face, facial and body hair growth, inconsistent menstruation in women, and decreased sexual urge in men. These could as well initiate a call for an ACTH stimulation test.
What are the risks associated with an ACTH stimulation test?
Most of the risks associated with an ACTH stimulation test stem from the actual step of getting your blood sample. Some common ones are; hematoma, infection, increased blood loss, lightheadedness, punctured vein’s inflammation, throbbing pain at the puncture site, a bruise at the puncture site, etc.
How you should prepare for an ACTH stimulation test
This might vary. You certainly will fast for some eight hours prior to the test time. You might also have to discontinue taking some medications 24 hours to the test time. Some of such medications are steroids, contraceptives, lithium, male hormones, amphetamines, estrogen, and anti-seizure drugs such as phenytoin.
You should inform your doctor if you are on any drug whatsoever at your first visit to him.
How is an ACTH stimulation test performed?
Your blood sample will be taken for the purpose of checking the amount of cortisol in your blood. This will be compared with that which will be drawn again from you after the test. The substance you will be injected with is cosyntropin. It has the ability to induce your adrenal glands to synthesize cortisol.
The outcome of the synthetic action of cosyntropin can take up to one hour to achieve. After this time, the second sample of your blood will be drawn. It is this second blood sample that will tell the injection’s effect after it must have been compared with the first. Your result might take a week or two to be ready for collection.
Interpreting the results
Normally, the level of cortisol in your blood should increase with this test if your adrenal glands are fine. It is possible for the results to have a slight variation. You should talk about that with your doctor.
If your cortisol levels were found out to be lower than normal, it might mean you have hypopituitarism, acute adrenal crisis, or Addison’s disease.
And if is extremely higher than what the normal should be, it might be an indication that you have Cushing’s syndrome.
These two cases will need further confirmatory diagnosis.
These confirmatory tests may be quite complicating. It will be fine if you can talk to your doctor or your healthcare provider. Doing so will position you to be rightly helped out on what to do.
Ifiokobong Ene is a Medical Physiologist, and a freelance medical writer. Ifiok brings his years of medical research experience to help consistently create high-quality, and engaging articles and products that uphold the highest medical standards. He is dedicated to making health and wellness information available, actionable, and understandable so that readers can make the best decisions about their health.