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Cosyntropin Stimulation Test

Sometimes, our adrenal glands don’t work the way they should. They’re supposed to produce hormones that perform various functions. Cortisol is a hormone that is normally secreted by the adrenal glands. Among other things, it helps you to respond to stress.

What is endocrinology?

Endocrinology is a specialty medical practice where the doctor treats disorders of the endocrine system. The endocrine system is a series of glands that secrete hormones into the bloodstream rather than a duct system.  Different hormones have different functions and effects on body organs. Hormones are chemicals. Some work independently on the functioning of one or more organs. Others have a preliminary role by stimulating the secretion of another hormone. For example, a thyroid-stimulating hormone will trigger the secretion of a secondary thyroid hormone. The secondary thyroid hormones regulate bodily functions including heart rate, blood pressure, respiration, metabolism, body temperature, and mood.

What is the function of adrenal glands?

Adrenal glands are small triangular glands located on the top of each kidney. They secrete cortisol, aldosterone, and adrenaline. Those hormones regulate blood pressure, immune system, metabolism, blood pressure, and your body’s response to stress. Adrenocorticotropic hormone (ACTH) is one of those primary hormones that stimulate other adrenal glands to release other hormones. It is secreted by the pituitary gland which is located behind your nose and is connected physically to your brain. ACTH works to send a signal to the adrenal glands to release cortisol.

How does cortisol work?

Cortisol is commonly called the stress hormone but it has several functions. For example, it:

• Regulates your body’s response to stress
• Regulates your blood pressure
• Regulates your blood sugar
• Reduces inflammation
• Regulates your metabolism
• Manages your sleep-wake cycle

ACTH also acts as a primary hormone that stimulates the release of androgens, adrenaline, and noradrenaline. Your brain is the ultimate signal caller, controlling your body functions. The hypothalamus part of your brain is connected to your pituitary gland. When your cortisol levels are low, the hypothalamus senses it and releases a CRH corticotrophin-releasing hormone. CRH stimulates your anterior pituitary lobe to secrete ACTH. ACTH then stimulates your adrenal cortex to release cortisol. An increased cortisol level works the opposite way by signaling to the hypothalamus to decrease CRH levels. The circuit is complete.

What is a cosyntropin stimulation test?

A cosyntropin stimulation test is used to determine if ACTH has the desired effect on your adrenal glands to regulate cortisol secretions. The test also determines if your pituitary and adrenal glands are working correctly.

When should a cosyntropin stimulation test be ordered?

The following symptoms might suggest the need for a cosyntropin stimulation test.

• Abnormal electrolyte level
• Abnormal thyroid test
• History of autoimmune disease.
• Low blood pressure
• Craving salt

How is the cosyntropin stimulation test administered?

The ACTH test is a blood test that measures the level of ACTH in your blood. ACTH levels usually peak in the morning and decline during the day. It reaches its lowest point around midnight. So blood is usually drawn in the morning. First, a baseline blood test is taken to determine the patient’s normal cortisol level. Then, a synthetic ACTH is injected into a muscle. An hour later, a blood sample is taken to measure the patient’s resulting cortisol level. If the post-injection cortisol level is elevated, it indicates that the adrenal glands responded normally to the ACTH injection. If the post-injection cortisol is not elevated it indicates that the adrenal glands are not functioning properly. Normal ACTH levels range from 7.2 to 63.3 picograms per milliliter in the morning. The levels will be different for people who usually work at night. If you have an abnormally high level of ACTH it is usually a symptom not a cause of some conditions. Those conditions include
• Cushing’s disease. This is a benign tumor in the pituitary gland causing it to produce too much ACTH and a corresponding increase in cortisol secretions.
• Ectopic adrenocorticotropic hormone tumor. This tumor is attached to the outside of the pituitary gland, causing it to overproduce ACTH.
• Primary adrenal insufficiency. Addison’s disease is an example. If your adrenal glands do not produce enough cortisol, your pituitary gland releases ACTH to stimulate your adrenal glands to produce more cortisol.

On the other hand, a low ACTH test can be a symptom of some other condition. They include:
• Cushing syndrome. Not to be confused with Cushing’s disease, the syndrome can be caused by an adrenal tumor or long-time use of corticosteroids. Too much cortisol keeps the pituitary gland from producing enough ACTH.
• Hypopituitarism. This condition is caused by harm to the pituitary gland. The injured pituitary gland produces an insufficient amount of one or more hormones it’s supposed to produce, including ACTH.


If you are experiencing any of the symptoms listed above, we encourage you to seek medical help immediately. They could indicate an excess or deficiency of ACTH. A simple cosyntropin stimulation test could reveal a serious underlying disorder of your endocrine system.

At Bay Area Endocrinology, we manage the most difficult adrenal gland disorders. Our offices are in the Tampa Bay area. We can determine if you need a cosyntropin stimulation test. If required, we can provide expert treatment for a disorder. Contact us today!

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