Cushing’s disease is a disorder of the pituitary gland in which too much adrenocorticotropic hormone (ACTH) is produced by a pituitary tumor, 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 (including long term-use of corticosteroid medications such as prednisone, ACTH-producing tumors outside the pituitary gland, and cortisol-producing adrenal tumors), but when the excess is being triggered by a pituitary tumor, the individual is diagnosed with Cushing’s disease. (Some 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 noradrenaline 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 after 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?
Cushing’s disease is most often caused by a benign pituitary tumor that produces ACTH, leading to excess of cortisol. Removing the tumor often halts the condition and reverses many of the symptoms. (Find out more about surgery for a pituitary tumor.)
Reviewed by: Georgiana Dobri, M.D.
Last reviewed/last updated: September 2023
Illustration by Thom Graves, CMI