Question: My doctor talks about the hypothalamic-pituitary-adrenal-system. What is this and what does it have to do with Cushing's?

Answer: The hypothalamic - pituitary -adrenal system is the body's normal system for producing cortisol. The hypothalamus, a part of the brain, produces a hormone called CRH. CRH travels to the pituitary gland, located just below, where it stimulates the production of ACTH. ACTH in turn stimulates the adrenal to produce cortisol. When circulating cortisol levels are high, both the hypothalamus and pituitary decrease their hormonal output. This normally causes a decrease in ACTH production, which decreases the amount of cortisol produced by the adrenal. With Cushing's, regardless of the cause, this system does not function properly, and cortisol levels rise.