Figure 1: The various causes of Cushing’s syndrome

Cushing’s disease In Cushing’s disease a pituitary tumor makes ACTH, which stimulates adrenal gland production of cortisol. High cortisol levels inhibit CRH secretion and ACTH secretion from normal pituitary cells.

Ectopic ACTH secretion In ectopic ACTH secretion, a non-pituitary tumor makes ACTH, which stimulates adrenal gland production of cortisol. High cortisol levels inhibit CRH secretion and ACTH secretion from normal pituitary cells.

Primary adrenal disease
In primary adrenal disease, the adrenal glands independently make too much cortisol. High cortisol levels inhibit CRH secretion and ACTH secretion from normal pituitary cells.
 

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