Vol- & Na-depleted patients by vigorous diuretic therapy, dietary salt restriction, diarrhoea or vomiting. Renovascular HTN, renal impairment & kidney transplantation, aortic or mitral stenosis or obstructive hypertrophic cardiomyopathy. Primary aldosteronism, hypertensive patients w/ type 2 diabetes & renal disease, hyperkalemia. May impair ability to drive or operate machinery.