What is Cushing's Disease?

Margo Upson
Margo Upson

Cushing's disease is a rare condition, affecting about 10 people out of one million, caused by excess cortisol in the body. Cortisol is most commonly known as the stress hormone, as it is produced during the body's natural "fight or flight" reflex. It also reduces inflammation, assists the liver in the removal of toxins, and helps the body to use salt properly. Too much cortisol in the body, however, can be dangerous to a person's health, causing problems like reduced immunity and decreased bone mass. If left untreated, Cushing's disease can lead to heart disease and possibly death.

An uncommon reason for too much cortisol is a tumor growth in the pituitary gland.
An uncommon reason for too much cortisol is a tumor growth in the pituitary gland.

Cushing's syndrome refers to the increase of cortisol levels due to one of two reasons. The first is as a side effect of taking glucocorticoid medications, such as asthma medications or other drugs that contain steroids. The second cause is the over-production of cortisol in the adrenal glands. This second type of Cushing's is called Cushing's disease. Although it is also seen in dogs and horses, it is most common in humans.

Insomnia can be a symptom of Cushing's disease.
Insomnia can be a symptom of Cushing's disease.

The over-production of cortisol in the adrenal glands is the result of a small non-cancerous tumor, called an adenoma, in the pituitary glands, which are located near the bottom of the brain. Pituitary glands control the adrenocorticotropic hormone (ACTH). ACTH is then carried to the adrenal glands, found near the kidneys. Based on the amounts of ACTH sent out, the adrenal glands produce the cortisol that the body needs.

The most common symptom of Cushing's disease is weight gain, predominantly in the trunk and around the face. Excess deposits of fat around the back of the neck, collar bone and in the face are frequently seen. An increased amount of sweating, insomnia, hypertension, and dry, thin skin are also common symptoms. Women may see an increase in hair growth and may suffer from irregular periods. High blood pressure, diabetes and longer healing times may also be symptoms of Cushing's disease.

Cushing's disease is diagnosed by comparing the levels of cortisol in a person's urine over a 24-hour period. Magnetic resonance imaging (MRI) and computated axial tomography (CAT) scans may also be used, in addition to the urine test. Once Cushing's disease has been confirmed, surgery will be scheduled. During the surgery, the tumors in the pituitary gland will be removed. Radiation treatments may be used for a short while after the surgery, to assure that the tumor will not reform. Steroid replacement medications will also be used until the pituitary glands begin functioning normally again.

Horses can be affected by Cushing's disease, just as can humans and dogs.
Horses can be affected by Cushing's disease, just as can humans and dogs.
Margo Upson
Margo Upson

Margo has a varied academic background, which has involved everything from psychology and culinary arts to criminal justice and education. These wide-ranging interests make her an ideal wiseGEEK writer, as she always enjoys becoming an expert on new and unfamiliar topics.

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Discussion Comments


My 13 year old grandson is about to be tested for cushing's disease. We are all so worried. I have never heard of this disease before.


My sister had steroid induced Cushing's disease. Thankfully, she's fine now. The condition reversed itself after she got off of the steroids. It was a difficult time for her though. She gained weight and also became depressed. We're so happy that she's okay now.


@turquoise-- Actually, diagnosing Chushing's disease is still very difficult. When this disease was first described by Harvey Cushing, his conclusions were based on the symptoms he saw in patients and his knowledge of the various glands and their functions. Obviously, this was the right method as it led to the discovery of the disease.

But the issue with diagnosing this disease based on symptoms alone is that only a small percentage of people with Cushing's disease actually experience the tell-tale signs. So diagnosis has to be done with multiple diagnostic testing. Even a single test like blood tests can be unsatisfactory. It's important to also run urine test, saliva test, etc. And if a tumor is suspected, then an MR is also required.

This process can be kind of long and frustrating for both the patient and the doctors. Doctors from several different branches need to work together for a definite diagnosis. Diagnosis today is definitely easier than diagnosis in the 1940s. But it's still not a simple process.


I had no idea that the cause of excessive cortisol production is a tumor. So actually, the cause of all of these symptoms and complications of this disease isn't excessive cortisol, but a tumor. Excessive cortisol is also a side effect of the tumor. It's sort of a process where the tumor causes the pituitary glands to malfunction which in turn cause the adrenal glands to malfunction and the patient experiences the myriad of symptoms caused by this.

We are so lucky that medicine has advanced far enough that these diseases are easily diagnosed and treated. I'm sure that before all this advancement, doctors and patients must have been baffled by these symptoms in someone with Cushing's disease.

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