Cushing's syndrome causes

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Associate Editor(s)-in-Chief: Furqan M M. M.B.B.S[2]

Cushing’s syndrome occurs when the body’s tissues are exposed to high levels of corticosteroids for a long period. Many people develop Cushing’s syndrome because they take glucocorticoids, (steroid hormones that are chemically similar to naturally produced cortisol) such as prednisone for asthma, rheumatoid arthritis, lupus, and other inflammatory diseases. Glucocorticoids are also used to suppress the immune system after transplantation to keep the body from rejecting the new organ or tissue. Other people develop Cushing’s syndrome because their bodies produce too much cortisol due to adrenal or extra-adrenal causes.

The major causes of Cushing’s syndrome are:^{[1][2][3][4][5]}

• Excess ACTH secretion
  • Pituitary Adenomas: These benign, or noncancerous, tumors of the pituitary gland secrete extra ACTH. Most people with the disorder have a single adenoma. This form of the syndrome is known as Cushing’s disease.
  • Ectopic ACTH Syndrome: Some benign or more often, cancerous tumors that arise outside the pituitary can produce ACTH. This condition is known as ectopic ACTH syndrome. Lung cancer causes more than half of these cases. Rarely, bronchial and thymic carcinoids also cause ectopic secretion of ACTH.
• Excess secretion of cortisol by adrenal glands:
  • Adrenal Tumors: In rare cases, an abnormality of the adrenal glands, most often an adrenal tumor, causes Cushing’s syndrome. Adrenal tumors are four to five times more common in women than men, and the average age of onset is about 40. Most of these cases involve noncancerous tumors of adrenal tissue called adrenal adenomas, which secrete excess cortisol.
  • Adrenocortical carcinomas (Adrenal cancers): These are the least common cause of Cushing’s syndrome. With adrenocortical carcinomas, cancer cells secrete excess levels of several adrenocortical hormones, including cortisol and adrenal androgens, a type of male hormone. Adrenocortical carcinomas usually cause very high hormone levels and rapid development of symptoms.

Familial Cushing’s Syndrome

• Most cases of Cushing’s syndrome are not inherited. Rarely, however, Cushing’s syndrome results from an inherited tendency to develop tumors of one or more endocrine glands. Endocrine glands release hormones into the bloodstream. With primary pigmented micronodular adrenal disease, children or young adults develop small cortisol-producing tumors of the adrenal glands. With multiple endocrine neoplasia type 1 (MEN1), hormone-secreting tumors of the parathyroid glands, pancreas, and pituitary develop; Cushing’s syndrome in MEN1 may be due to pituitary, ectopic, or adrenal tumors.

The following drugs can also cause the Cushing’s syndrome.

• Betamethasone dipropionate
• Betamethasone valerate
• Dexamethasone
• Prednisolone
• Ritonavir
• Triamcinolone
• Diflorasone
• Amcinonide

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