What Is Cushing's Syndrome?
Cushing's syndrome is a rare condition. Out of one million people, approximately 5 to 25 cases of Cushing's syndrome are diagnosed each year. Of those diagnosed, more than 70% are women between 20 and 50 years old.1,2
What causes Cushing's syndrome?
Cushing's syndrome is a result of high levels of cortisone-type steroids in the body.2,3 It can be caused by taking high doses of steroid medications for a long period of time or by an overproduction of a hormone called cortisol in the body.1-4
When the body produces too much cortisol, it's usually caused by a tumor of the pituitary gland. These tumors produce a hormone called ACTH (adrenocorticotropic hormone) that causes the adrenal glands to produce and secrete too much cortisol.1-3,5
The adrenal glands are located above each kidney and release cortisol into the bloodstream. Cortisol regulates metabolism, helps the body deal with stress, reduces the body's inflammatory response, and helps balance the effects of insulin. But high levels of cortisol in your blood for too long can cause Cushing's syndrome.6
CUSHING'S SYNDROME VS CUSHING'S DISEASE
When high levels of cortisol are detected in the body over an extended period of time, it's called Cushing's syndrome.1,2,4,5 When the high levels of cortisol are caused by a tumor of the pituitary gland, it's called Cushing's disease.1,2,4,5
It's important to note that Cushing's disease is a specific form of Cushing's syndrome, so the two terms are not interchangeable.5
CUSHING'S SYNDROME: ENDOGENOUS VS EXOGENOUS
There are two types of Cushing's syndrome:
1) Endogenous Cushing's Syndrome
When there is an overproduction of cortisol in the body, it's referred to as endogenous Cushing's syndrome.3 Usually this is caused by a tumor. These tumors are usually benign (noncancerous), but may be cancerous.2
Here are the different types of endogenous Cushing's syndrome:
Pituitary tumor (Cushing's disease)
Cushing's disease constitutes about 70% of Cushing's syndrome cases and is caused by a tumor of the pituitary gland.2 The pituitary is a small pea-sized gland on the underside of the brain.7
Pituitary tumors that cause Cushing's disease result in too much production of the hormone ACTH, which then causes the adrenal glands to make too much cortisol.2,3
- Non-pituitary ACTH-secreting tumor (ectopic ACTH syndrome)2
This is a tumor located in some other part of the body (not in the pituitary), which produces high levels of ACTH, thus triggering the adrenal glands to produce excess levels of cortisol.1,3
- Adrenal tumor
A cortisol-producing tumor of the adrenal glands.2
2) Exogenous Cushing's Syndrome
Exogenous Cushing's syndrome is caused when steroid medications, such as cortisone, are given in high doses over long periods of time for the treatment of some other disease, like asthma or rheumatoid arthritis.1-3,5
- Adrenal diseases: Cushing's syndrome. The facts you need to know. National Adrenal Diseases Foundation Web site. http://www.nadf.us/diseases/cushings.htm. Accessed April 13, 2013.
- Cushing's syndrome/disease. American Association of Neurological Surgeons Web site. http://www.aans.org/en/Patient%20Information/Conditions%20and%20Treatments/Cushings%20Disease.aspx. Accessed April 13, 2013.
- Nieman LK, Biller BMK, Findling JW, et al, eds. The Diagnosis of Cushing's Syndrome: An Endocrine Society Clinical Practice Guideline. Chevy Chase, MD: The Endocrine Society; 2008. https://www.endocrine.org/~/media/endosociety/Files/Publications/Clinical%20Practice%20Guidelines/Cushings_Guideline.pdf. Accessed April 13, 2013.
- Cushing's Syndrome and Cushing's Disease: Your Question's Answered. The Pituitary Society Web site. http://www.pituitarysociety.org/public/specific/cushing/cushings.pdf. Accessed April 13, 2013.
- Frequently asked questions about transsphenoidal surgery for pituitary adenomas. Massachusetts General Hospital Web site. http://www.massgeneral.org/neurosurgery/services/faq_transsphenoidalsurgery_cushingdisease.aspx. Accessed April 13, 2013.
- Cushing's syndrome. National Endocrine and Metabolic Diseases Information Service Web site. http://endocrine.niddk.nih.gov/pubs/cushings/cushings.aspx. Accessed April 13, 2013.
- Pituitary tumor. MedlinePlus Web site. http://www.nlm.nih.gov/medlineplus/ency/article/000704.htm. Updated November 23, 2009. Accessed April 15, 2013.