Which of the following statements about Cushing's disease is true?: (A) Serum adrenocoicotropin (ACTH) levels usually are low, (B) Pituitary microadenoma usually is present, (C) There is a high incidence of nonendocrine tumors, (D) Nonsuppression of coisol production by the high-dose dexamethasone suppression test is a characteristic finding
Answer is B. Cushing's syndrome is due to increased adrenal coisol production, regardless of aetiology.Cushing's disease usually is caused by a pituitary microadenoma producing high adrenocoicotropin (ACTH) levels.In most patients, coisol levels would be suppressed as a result of the high-dose dexamethasone suppression test.Transsphenoidal microsurgical removal of the microadenoma is the treatment of choice in most centres.