Cushing Syndrome

• Cushing Syndrome Overview
• Cushing Syndrome Causes
• Cushing Syndrome Symptoms
• Exams and Tests for Cushing Syndrome
• Cushing Syndrome Treatment
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Cushing Syndrome Overview

Cushing syndrome is a disorder caused by prolonged exposure of the body's tissues to high levels of corticosteroids (glucocorticoids).

Corticosteroids are powerful steroid hormones produced by the adrenal glands, located above each kidney. They regulate the metabolism of proteins, carbohydrates, and fats. They reduce the immune system's inflammatory responses and help to maintain blood pressure and heart function. A vital function of corticosteroids is to help the body respond to stress.

Corticosteroid production by the adrenal glands follows a sequence of events. The hypothalamus (see Anatomy of the Endocrine System) releases corticotropin-releasing hormone (CRH), which causes the pituitary gland to secrete adrenocorticotropic hormone (ACTH), which in turn stimulates the adrenal glands to produce corticosteroid. When the corticosteroid level is low, more CRH and ACTH are produced; when the corticosteroid level is high, less CRH and ACTH are produced. Under normal conditions, the corticosteroid level and CRH/ACTH levels are in dynamic balance; Cushing disease occurs when that balance is disturbed.

Excess corticosteroids have detrimental effects on many of the tissues and organs of the body. All of these effects together are called Cushing syndrome.

Overproduction of corticosteroids can be caused by a tumor in the pituitary gland, which produces excess ACTH, thereby stimulating the adrenal gland to produce excess corticosteroids. This condition is called Cushing disease because the origin is in the hypothalamic pituitary system. Cushing syndrome is a collection of symptoms which look and act like Cushing disease but is not the result of pituitary ACTH overproduction.

Endogenous Cushing syndrome is the result of autonomous, unregulated production of corticosteroids by a tumor within one or both of the adrenal glands themselves. The most common cause of Cushing syndrome, however, is exogenous Cushing syndrome, which results from taking excessive amounts of corticosteroid drugs.

The majority of cases of Cushing syndrome are caused by administration of corticosteroids (exogenous) for the treatment of long-term diseases such as asthma, arthritis, and lupus.