Siddiqui M, Judd EK, Dudenbostel T, et al. - Researchers sought to determine, for the first time, the prevalence of true refractory hypertension (RfHTN), a phenotype of antihypertensive treatment failure defined as uncontrolled BP despite the use of effective doses of ≥ 5 antihypertensive medications including a long-acting thiazide-like diuretic (chlorthalidone) and a mineralocorticoid receptor antagonist. Further, they determined the degree of medication nonadherence among patients with RfHTN. From the University of Alabama at Birmingham Hypertension Clinic, they evaluated 54 patients with apparent RfHTN after having uncontrolled BP at 3 or more clinic visits. Automated office BP and 24-hour ambulatory BP monitoring were done to determine BP in all patients (n = 49). They performed measurement of 24-hour urine specimens for antihypertensive medications and their metabolites by high-performance liquid chromatography-tandem mass spectrometry (n = 45) for determining antihypertensive medication adherence. This study revealed adherence to 5 antihypertensive medications, including a long-acting thiazide like diuretic and a mineralocorticoid receptor antagonist, in 52.5% of patients with apparent refractory hypertension. Findings here verify the prevalence of true RfTHN based on sufficient medication adherence. This study suggests that although rare, RfTHN is a true phenotype of antihypertensive treatment failure.