My answer is “no.” Although primary aldosteronism (PA) is likely more common than most experts believed in the 1960–1990 interval, it is not nearly as common as Dr Calhoun and other investigators report from 1990 until now. As many younger clinicians may not remember, this same issue arose soon after Dr Jerome Conn characterized this disease in 1955.1 Reporting on the prevalence of PA in his highly referred population of likely suspects, Dr Conn and coworkers’ estimates were as high as 20%.2 Subsequently, studies on unreferred patients supported a prevalence of <1%.3 The lower estimate was commonly accepted until Gordan and colleagues started screening for PA with the plasma aldosterone:renin ratio (ARR) first described in 19764 and expanded by Hiramatsu et al in 1981.5 In 1993, Gordon et al6 reported an elevated ARR in 20% of 199 patients, with 8.5% having an abnormal saline suppression test and 2.5% proven to have an aldosterone-producing adenoma. Since then, numerous series have been reported (Table). As seen in Table 1, the prevalence of an elevated ARR has varied from 5.5% to 39.0%. Part of the wide variation rises from the use of varying thresholds; more of the variation rises from inclusion of various types of patients. The latter point must be recognized, because most patients in these series were referred to specialized centers, just as Dr Conn’s high numbers were largely derived from a referred population. View this table: Prevalence of Autonomous Hyperaldosteronism and APAs in Patients Tested by ARR Two recently published series epitomize the vagaries of most series listed in the Table. The first is a study of 1125 recently diagnosed subjects with hypertension referred to 14 specialized hypertension clinics throughout Italy.27 Plasma renin activity and plasma aldosterone were measured at baseline and again 60 …