Which of the following statements about Cushing’s disease is true?: (A) Serum adrenocorticotropin (ACTH) levels usually are low, (B) Pituitary microadenoma usually is present, (C) There is a high incidence of nonendocrine tumors, (D) Nonsuppression of cortisol production by the high-dose dexamethasone suppression test is a characteristic finding
Answer is B. Cushing’s syndrome is due to increased adrenal cortisol production, regardless of etiology.
Cushing’s disease usually is caused by a pituitary microadenoma producing high adrenocorticotropin (ACTH) levels.
In most patients, cortisol 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 centers.