Cushing's Disease

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The pituitary gland is often called “the master gland” because of its role in regulating the complex interplay of hormones. When the gland malfunctions, or when it develops a tumor that secretes cortisol, the result is Cushing’s disease.

Cushing’s disease is a disorder of the pituitary gland in which too much adrenocorticotropic hormone (ACTH) is produced, which in turn stimulates excess production of the stress hormone cortisol.

Cushing’s disease is one form of Cushing syndrome, which is the condition that results from overexposure to cortisol. Not everyone with Cushing syndrome has Cushing’s disease. Several things may cause high levels of cortisol, but when the excess is being produced by the body due to a pituitary tumor or a malfunction that results in excess growth of the gland, the individual is diagnosed with Cushing’s disease. (Many tumors of the pituitary gland are “functioning” tumors, meaning that they take on a function of the gland itself by producing a hormone.)

Cortisol plays a role in the evolutionary “fight or flight” response — the hormone is released along with adrenaline and norepinephrine in short-term stress situations. A surge of cortisol helps the body respond to an immediate threat, but the hormone has negative effects when produced continually instead of in short bursts. An individual exposed to excess cortisol levels on an ongoing basis may develop a characteristic “moon face” (moon facies), upper-body obesity and fat deposits, muscle weakness, and bone thinning, among other symptoms. Left untreated, Cushing’s disease can ultimately be fatal, but fortunately there are effective treatments for the disorder. (See Diagnosing and Treating Cushing’s Disease.)

Both Cushing’s disease and Cushing syndrome are named for Harvey Williams Cushing, a prominent neurosurgeon in the early twentieth century who is often called “the father of modern neurosurgery.” Dr. Cushing was a pioneering investigator of pituitary function and dysfunction, and he was the first to associate the pituitary gland with the classic symptoms of the disorders named for him.

What Causes Cushing’s Disease?
An overproduction of cortisol can be caused by a number of things (including long-term use of prednisone or other corticosteroids), but the specific disorder called Cushing’s disease is most often caused by a benign pituitary tumor that produces cortisol. Removing the tumor often resolves the condition. (Find out more about surgery for a pituitary tumor.)

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Reviewed by: Theodore Schwartz, M.D.
Last reviewed/last updated: January 2015
Illustration by Thom Graves, CMI