Cushing's Syndrome Health Article

Definition

Cushing's syndrome is a relatively rare endocrine (hormonal) disorder resulting from excessive exposure to the hormone cortisol. The disorder, which leads to a variety of symptoms and physical abnormalities, is most commonly caused by taking medications containing the hormone over a long period of time. A more rare form of the disorder occurs when the body itself produces an excessive amount of cortisol.

Description

The adrenals are two glands, each of which is perched on the upper part of the two kidneys. The outer part of the gland is known as the cortex; the inner part is known as the medulla. Each of these parts of the adrenal gland is responsible for producing different types of hormones. Regulation of hormone production and release from the adrenal cortex involves the pituitary gland, a small gland located at the base of the brain. After the hypothalamus (the part of the brain containing secretions important to metabolic activities) sends "releasing hormones" to the pituitary gland, the pituitary secretes a hormone called adrenocorticotropic hormone (ACTH). The ACTH then travels through the bloodstream to the adrenal cortex, where it encourages the production and release of cortisol (sometimes called the "stress" hormone) and other adrenocortical hormones.

Cortisol, a very potent glucocorticoid—a group of adrenocortical hormones that protects the body from stress and affect protein and carbohydrate metabolism— is involved in regulating the functioning of nearly every type of organ and tissue in the body, and is considered to be one of the few hormones absolutely necessary for life. Cortisol is involved in:

• complex processing and utilization of many nutrients, including sugars (carbohydrates), fats, and proteins
• normal functioning of the circulatory system and the heart
• functioning of muscles
• normal kidney function
• production of blood cells
• normal processes involved in maintaining the skeletal system
• proper functioning of the brain and nerves
• normal responses of the immune system

Cushing's syndrome, also called hypercortisolism, has an adverse effect on all of the processes described above. The syndrome occurs in approximately 10 to 15 out of every one million people per year, usually striking adults between the ages of 20 and 50.

Causes and symptoms

The most common cause of Cushing's syndrome is the long-term use of glucocorticoid hormones in medications. Medications such as prednisone are used in a number of inflammatory conditions. Such conditions include rheumatoid arthritis, asthma, vasculitis, lupus, and a variety of other autoimmune disorders in which the body's immune cells accidentally attack some part of the body itself. In these disorders, the glucocorticoids are used to dampen the immune response, thereby decreasing damage to the body.

Cushing's syndrome can also be caused by three different categories of disease:

• a pituitary tumor producing abnormally large quantities of ACTH
• the abnormal production of ACTH by some source other than the pituitary
• a tumor within the adrenal gland overproducing cortisol

Although it is rare, about two-thirds of endogenous (occurring within the body rather than from a source outside the body, like a medication) Cushing's syndrome is a result of Cushing's disease. The term "Cushing's disease" refers to Cushing's syndrome, which is caused by excessive secretion of ACTH by a pituitary tumor, usually an adenoma (noncancerous tumor). The pituitary tumor causes increased growth of the adrenal cortex (hyperplasia) and increased cortisol production. Cushing's disease affects women more often than men.

Tumors in locations other than the pituitary can also produce ACTH. This is called ectopic ACTH syndrome ("ectopic" refers to something existing out of its normal place). Tumors in the lung account for more than half of all cases of ectopic ACTH syndrome. Other types of tumors which may produce ACTH include tumors of the thymus, the pancreas, the thyroid, and the adrenal gland. In each case, the secreting part of the tumor may be in the primary tumor, part of the primary tumor, or may be a small, difficult-to-find, metastatic lesion (s). Nearly all adrenal gland tumors are benign (noncancerous), although in rare instances a tumor may actually be cancerous.

Symptoms of cortisol excess (resulting from medication or from the body's excess production of the hormone) include:

• weight gain
• an abnormal accumulation of fatty pads in the face (creating the distinctive "moon face" of Cushing's syndrome); in the trunk (termed "truncal obesity"); and over the upper back and the back of the neck (giving the individual what has been called a "buffalo hump")
• purple and pink stretch marks across the abdomen and flanks
• high blood pressure
• weak, thinning bones (osteoporosis)
• weak muscles
• low energy
• thin, fragile skin, with a tendency toward both bruising and slow healing
• abnormalities in the processing of sugars (glucose), with occasional development of actual diabetes
• kidney stones
• increased risk of infections
• emotional disturbances, including mood swings, depression, irritability, confusion, or even a complete break with reality (psychosis)
• irregular menstrual periods in women
• decreased sex drive in men and difficulty maintaining an erection
• abormal hair growth in women (in a male pattern, such as in the beard and mustache area), as well as loss of hair from the head (receding hair line).