Cushing's Syndrome

Cushing's syndrome is a condition that occurs when the body is exposed to high levels of the hormone * cortisol. Symptoms may include muscle weakness, weight gain, a round face (often referred to as a moon face), the growth of fat pads in specific places (along the collar bone and at the back of the neck), extra body fat, the growth of facial and body hair, and emotional problems.

Cushing's syndrome occurs when the body is exposed to high levels of the hormone cortisol for long periods. Cortisol is often called the “stress hormone” because its level in the body rises in response to stress. In the healthy individual, cortisol helps to manage stress and to repair its ill effects. Cortisol helps regulate blood pressure and the metabolism, which is the sum total of all of the chemical reactions occurring in cells (including the conversion of food into energy and waste products). Cortisol also plays a role in immune system responses to stress. As with most hormones, the amount of cortisol in the body must be closely controlled, as either too much or too little cortisol has negative effects on the body.

In a healthy person, cortisol production is regulated by the interactions of three parts of the endocrine * system:

The most common cause of Cushing's syndrome is long-term treatment (daily doses for weeks or months) with drugs that are chemically related to cortisol and can be converted into cortisol by the body. These drugs as a group are referred to as steroids, glucocorticoid-based drugs, or cortisone-like drugs. Prednisone is a common example. Glucocorticoid-based drugs are used to treat chronic inflammation * in disorders such as asthma * , rheumatoid arthritis * , lupus * , and other less common inflammatory diseases.

Some pituitary tumors can produce increased amounts of ACTH, which in turn causes the adrenal glands to produce excess cortisol. This form of the syndrome is known as Cushing's disease. Most of the ACTH-secreting tumors of the pituitary are not cancerous, and most affected people have only a single tumor. The tumors are five times more likely to occur in women than in men. Cushing's disease accounts for about 70 percent of all cases of Cushing's syndrome not caused by glucocorticoid-based therapies.

Tumors that arise elsewhere in the body, such as in the lungs, can also produce ACTH. Most ACTH-producing tumors located outside the pituitary gland are cancerous (malignant). In rare cases, tumors of the adrenal tissue itself cause excess cortisol production. Although most cases of Cushing's syndrome are not inherited, the tendency to develop tumors can be inherited.

The signs and symptoms of Cushing's syndrome are the same whether the syndrome is caused by drug therapy or tumor secretion. These include the following:

A doctor who sees a patient with symptoms suggestive of Cushing's syndrome will ask questions about the person's medical history and medications being taken and perform a physical examination. Three specific laboratory tests that involve analysis of cortisol levels in the blood and urine are commonly used to measure cortisol levels. If cortisol levels are high, other tests are done to find out why. For example, imaging techniques for looking inside the body (such as CT scans * and MRIs * ) can be used to look for tumors.

The treatment of tumors varies, depending on the tumor's location and whether it is cancerous. Noncancerous pituitary tumors are often successfully removed surgically. Cancerous tumors or pituitary tumors that cannot be operated on may be treated with radiation therapy or chemotherapy * , depending on the location of the tumor and the patient's general health. Additionally, Cushing's syndrome sometimes is treated with drugs that inhibit cortisol production.

If Cushing's syndrome occurs as a by-product of drug therapy, doctors will try to alter the drug dosage by reducing it, adjusting the patient's medication schedule so that there is less frequent dosing, or changing the medication to minimize the side effects of the drugs. Cortisol-inhibiting drugs may also be given.

Modifications of drug regimens (in the case of illness caused by drug therapies) and surgical removal of tumors can lead to a full recovery, although sometimes the tumors recur. When pituitary tumors are removed, the patient's level of ACTH may drop below normal. In such a case the patient must take doses of supplemental cortisol, until ACTH production returns to normal.

See also Metabolic Disease • Obesity • Osteoporosis

* hormone is a chemical substance that is produced by a gland and sent into the bloodstream carrying messages that have certain effects on other parts of the body.

* endocrine (EN-do-krin) refers to a group of glands, such as the thyroid, adrenal, and pituitary glands, and the hormones they produce. The endocrine glands secrete their hormones into the bloodstream, and the hormones travel to the cells that have receptors for them. Certain hormones have effects on mood and sometimes cause emotional swings.

* inflammation (in-fla-MAY-shun) is the body's reaction to irritation, infection, or injury that often involves swelling, pain, redness, and warmth.

* asthma (AZ-mah) is a condition in which the airways of the lungs repeatedly become narrowed and inflamed, causing breathing difficulty.

* rheumatoid arthritis (ROO-mahtoyd ar-THRY-tis) is a chronic disease characterized by painful swelling, stiffness, and deformity of the joints.

* lupus (LOO-pus) is a chronic, or long-lasting, disease that causes inflammation of connective tissue, the material that holds together the various structures of the body.

* stretch marks are stripes or lines on the skin (such as on the hips, abdomen, and breasts) from excessive stretching and rupture of elastic fibers, especially due to pregnancy or obesity.

* susceptibility (su-sep-ti-BIL-i-tee) means having less resistance to and higher risk for infection or disease.

* CT scans, computed tomography (to-MOG-ra-fee) scans, or CAT (computerized axial tomography) scans, use computers to view structures inside the body.

* MRI short for magnetic resonance imaging, produces computerized images of internal body tissues based on the magnetic properties of atoms within the body.

* chemotherapy (KEE-mo-THER-apee) is the treatment of cancer with powerful drugs that kill cancer cells.