cushing disease is synonymous with hypercortisolism. it is secondary hypercotisolism which means the problems starts from the pituitary gland (not the adrenal gland). in excess of ACTH from the pituitary, the cortisol level in z.fasciculata increases as well.
your question is if its hypokalemic and why?
u see, when the ACTH rises, it affects the z.fasciculata right? in this zone, before cortisol is made, a weak mineralocorticoid (11-deoxycorticosterone) is made in excess (due to the very high ACTH). so this high levels of weak mineralocorticoid works just as well as high levels of aldosterone. which will cause Na+ retention along with H2O (hypertension), secretion of H+ (which will cause alkalosis) and secretion of K+ (hypokalemia).
so all in all, cushind disease causes hypertension, hypokalemia and met. alkalosis.
the 2 MUST remember adrenal related syndromes/diseases for the USMLE step 1 are cushing disease and addison disease (primary dificiency of cortisol). also u should remember that when they say primary adrenal, its from the adrenal, and secondary means the pituitary related.
good luck!! pls understand cushing disease and addison disease well!!
