The paucity of patients with low plasma aldosterone and low plasma renin in our study is consistent with aldosterone having a primary role in many patients with resistant hypertension.14, 21 However, none of the patients, even one whose hypertension was cured by removal of a 7 mm aldosterone-producing adenoma,22 exhibited the triad of spontaneous hypokalaemia, completely suppressed renin, and plasma aldosterone of more than 550 pmol/L that is currently required for diagnosis of primary aldosteronism if a suppression test (the alternative method of diagnosis) is to be avoided.21 This evidence concerns the gene REN and primary aldosteronism.