Definition and Causes of Cushing's Syndrome

Cushing’s Syndrome

Definition: Cushing’s Syndrome (also known as hypercorticolism) is a hormonal disorder caused by prolonged exposure of the body’s tissues to high levels of the hormone cortisol, either produced excessively by the body or through excessive intake of cortisol or other steroid hormones.

What Causes Cushing’s Syndrome?

1. Pituitary Adenomas

- most common cause (also known as Cushing’s Disease)

- benign tumors or hyperplasia of the pituitary gland, secreting increase amounts of ACTH

- affects women five times more frequently than men, and usually as a single adenoma

2. Ectopic ACTH Syndrome

- benign or malignant tumors that arise outside the pituitary gland producing ACTH

- most common is lung tumors ( >50% of ectopic cases), usually by small cell lung cancer

- thyromas, pancreatic islet cell tumors, medullary carcinomas of the thyroid (C cells)

3. Adrenal Tumors

- more commonly Adrenal Adenomas which releases excess cortisol

- Adrenocortical carcinomas, least common cause, secrete excess levels of several adrenal cortical hormones including cortisol and adrenal androgens. Cause very high hormone levels and rapid development of symptoms

4. Intake Of Glucocorticoid Hormones

- also known as Exogenous Cushing’s Syndrome

- due to intake of glucocorticoids such as prednisone or dexamethasone for treatment purposes

- for asthma, rheumatoid arthritis, lupus, inflammatory diseases, immunosuppression after transplantation

5. Familial Cushing’s Syndrome

- very rare; due to inherited tendency to develop tumors of one or more endocrine glands

- Primary Pigmented Micronodular Adrenal Disease: children or young adults develop small cortisol-producing tumors of the adrenal glands

- Multiple Endocrine Neoplasia Type I (MEN I): due to pituitary, ectopic or adrenal tumors

References

http://endocrine.niddk.nih.gov/pubs/cushings/cushings.htm

http://www.nlm.nih.gov/medlineplus/ency/article/000410.htm