<prompt> About cushing syndrome, true Is -Low dose dexamethasone suppress coisone secretionCA of adrenal is more common than adenomaPituitary adenoma size 2 cm usuallyACTH secretion is the commonest cause  <response>: most cases the cause is bilateral adrenal hyperplasia due to hyper secretion of pituitary ACTH or ectopic production of ACTH by a non pituitary source Harrison 17 pg 2255 