Refractory Hypertension, also known as a refractory hypertensive state, RfHTN, or status angiotensus, is a hypertensive condition which can occur, for no apparent reason, in patients with previously well-managed hypertension. Refractory hypertension is characterized by a blood pressure that remains uncontrolled on maximal or near-maximal therapy, which is the use of ≥5 antihypertensive agents of different classes, including a long-acting thiazide-like diuretic (such as chlorthalidone) and spironolactone. Patients with refractory hypertension typically exhibit increased sympathetic nervous system activity.The phenotype of refractory hypertension was first proposed in a retrospective analysis of patients referred to the University of Alabama at Birmingham Hypertension Clinic whose blood pres