<prompt> Answer this question truthfullyWhat is the significance of high dose dexamethasone 8 mg in cortisol suppression, and what conditions are characterized by cortisol suppression or lack thereof?  <response>: <reason> Lack of cortisol suppression with high dose dexamethasone 8 mg is characteristic of ectopic ACTH production small cell, while cortisol suppression is characteristic of Cushing Disease. 