Cushing's syndrome is an endocrine disease with increased secretion of cortisol.

Cortisol is a steroid hormone (corticosteroid) secreted by the outer cortex of the adrenal gland from cholesterol, dependent on Adreno CorticoTropic Hormone (ACTH) of hypophysis. 

The chronic glucocorticoid excess that leads to the various manifestations of this syndrome may be due :

• to pharmacological doses of corticosteroids from outside the body;  

• to a source of cortisol from within the organism.