Administration of synthetic ACTH is also possible, but ACTH is less often prescribed due to cost and lesser utility. Rarely, Cushings syndrome can also be due to the use of medroxyprogesterone acetate. In exogenous Cushings, the adrenal glands may often gradually atrophy due to lack of stimulation by ACTH, the production of which is suppressed by glucocorticoid medication. Abruptly stopping the medication can thus result in acute and potentially life-threatening adrenal insufficiency and the dose must hence be slowly and carefully tapered off to allow internal cortisol production to pick up. In some cases, patients never recover sufficient levels of internal production and must continue taking glucocorticoids at physiological doses for life.Cushings syndrome in childhood is especially rare and usually results from use of glucocorticoid medication. Endogenous
Endogenous Cushings syndrome results from some derangement of the bodys own system of cortisol secretion. Normally, ACTH is released from the pituitary gland when necessary to stimulate the release of cortisol from the adrenal glands. In pituitary Cushings, a benign pituitary adenoma secretes ACTH. This is also known as Cushings disease and is responsible for 70% of endogenous Cushings syndrome. In adrenal Cushings, excess cortisol is produced by adrenal gland tumors, hyperplastic adrenal glands, or adrenal glands with nodular adrenal hyperplasia. Tumors outside the normal pituitary-adrenal system can produce ACTH (occasionally with CRH) that affects the adrenal glands. This etiology is called ectopic or paraneoplastic Cushings disease and is seen in diseases such as small cell lung cancer.
This clinical situation is known as Nelsons syndrome. Epidemiology
Cushings syndrome caused by treatment with corticosteroids is the most common form. Cushings disease is rare; a Danish study found an incidence of less than one case per million people per year. However, asymptomatic microadenomas (less than 10 mm in size) of the pituitary are found in about one in six individuals.People with Cushings syndrome have increased morbidity and mortality as compared to the general population. The most common cause of mortality in Cushings syndrome is cardiovascular events. People with Cushings syndrome have nearly 4 times increased cardiovascular mortality as compared to the general population.About 0.9 to 1% of those with Cushings syndrome has tendency to develop venous thrombosis. Other factors such as surgery and obesity also increases the chance of getting thrombosis. Other animals
For more information on the form in horses, see pituitary pars intermedia dysfunction. See also
Addisons disease
Adrenal insufficiency (hypocortisolism)
Corticosteroid-induced lipodystrophy

References
External links
"Cushings Syndrome". MedlinePlus. U.S. National Library of Medicine.