Causes of Cushing's syndrome

Cause of Cushing's syndrome: Cushing's syndrome occurs when the body's tissues are exposed to excessive levels of cortisol for long periods of time. ¹

It may be caused by either prolonged exposure of the body's tissues to high levels of the hormone cortisol or by the overproduction of cortisol in the body. ²

Cause details for Cushing's syndrome: Cushing's syndrome occurs when the body's tissues are exposed to excessive levels of cortisol for long periods of time. Many people suffer the symptoms of Cushing's syndrome because they take glucocorticoid hormones such as prednisone for asthma, rheumatoid arthritis, lupus or other inflammatory diseases.

Others develop Cushing's syndrome because of overproduction of cortisol by the body. Normally, the production of cortisol follows a precise chain of events. First, the hypothalamus, a part of the brain which is about the size of a small sugar cube, sends corticotropin releasing hormone (CRH) to the pituitary gland. CRH causes the pituitary to secrete ACTH (adrenocorticotropin), a hormone that stimulates the adrenal glands. When the adrenals, which are located just above the kidneys, receive the ACTH, they respond by releasing cortisol into the bloodstream.

Cortisol performs vital tasks in the body. It helps maintain blood pressure and cardiovascular function, reduces the immune system's inflammatory response, balances the effects of insulin in breaking down sugar for energy, and regulates the metabolism of proteins, carbohydrates, and fats. One of cortisol's most important jobs is to help the body respond to stress. For this reason, women in their last 3 months of pregnancy and highly trained athletes normally have high levels of the hormone. People suffering from depression, alcoholism, malnutrition and panic disorders also have increased cortisol levels.

When the amount of cortisol in the blood is adequate, the hypothalamus and pituitary release less CRH and ACTH. This ensures that the amount of cortisol released by the adrenal glands is precisely balanced to meet the body's daily needs. However, if something goes wrong with the adrenals or their regulating switches in the pituitary gland or the hypothalamus, cortisol production can go awry. ¹

Underlying condition causes of Cushing's syndrome: The list of possible underlying conditions (see also Misdiagnosis of underlying causes of Cushing's syndrome) mentioned in various sources as possible causes of Cushing's syndrome includes:

Pituitary tumors
Pituitary adenomas (type of Adenoma) - usually benign ACTH-producing tumors of the pituitary gland; most common in women
ACTH-producing pituitary tumor
Lung tumors - more common in men
Small cell lung cancer (type of Lung cancer)
Thymoma (type of Thymus Cancer)
Pancreatic islet cell tumor
Thyroid medullary carcinoma
Adrenocortical carcinomas (type of Adrenal Cancer)
Adrenal gland tumor
Adrenal adenomas - benign adrenal tumor
Familial Cushing's Syndrome
Multiple Endocrine Neoplasia Type I
Primary Pigmented Micronodular Adrenal Disease
Carney's complex
McCune-Albright syndrome

Cushing's syndrome as a complication: Other conditions that might have Cushing's syndrome as a complication might be potential underlying causes of Cushing's syndrome. The list of conditions listing Cushing's syndrome as a complication in our database includes:

McCune-Albright Syndrome

Related information for causes of Cushing's syndrome: Further relevant information on causes of Cushing's syndrome may be found in the risk factors for Cushing's syndrome and underlying causes of Cushing's syndrome.

Footnotes:
1. excerpt from Cushing's Syndrome: NIDDK
2. excerpt from NINDS Cushing's Syndrome Information Page: NINDS

Last revision: May 26, 2003

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