Cushing's Syndrome Causes
Causes of Cushing's syndrome include anything that makes the body produce excessive levels of cortisol. The most common Cushing's syndrome causes are pituitary adenomas -- tumors in the pituitary gland. Adrenal tumors and ectopic ACTH syndrome are other possible causes of Cushing's syndrome. In very rare cases, people can develop Cushing as a result of a hereditary condition that causes them to develop endocrine tumors.
Cushing's syndrome occurs when the body's tissues are exposed to excessive levels of cortisol for long periods.
Cushing's syndrome can be caused by taking glucocorticoid hormones, such as prednisone, for:
- Rheumatoid arthritis
- Systemic lupus erythematosus (SLE or lupus) and other inflammatory diseases
- Immunosuppression after transplantation.
Other people may develop Cushing's syndrome because of an overproduction of cortisol by the body. Some of the common causes of Cushing's syndrome in which the body produces too much cortisol include:
- Pituitary adenomas
- Adrenal tumors
- Ectopic ACTH syndrome
- Familial Cushing's syndrome.
In most cases, Cushing's syndrome is caused by a pituitary adenoma. These are benign, or non-cancerous, tumors of the pituitary gland that secrete increased amounts of ACTH (adrenocorticotropin). Most patients have a single adenoma. This form of the syndrome, known as "Cushing's disease," affects women five times more frequently than men.
Sometimes, an abnormality of the adrenal glands -- most often an adrenal tumor -- causes Cushing's syndrome. The average age of onset is about 40 years. Most of these cases involve non-cancerous tumors of adrenal tissue, called adrenal adenomas, which release excess cortisol into the blood.
Adrenocortical carcinomas, or adrenal cancers, are the least common cause of Cushing's syndrome. Cancer cells secrete excess levels of several adrenal cortical hormones, including cortisol and adrenal androgens. Adrenocortical carcinomas usually cause very high hormone levels and a rapid development of symptoms.