Roughly 16%-22% of patients with hypertension appeared to have primary aldosteronism as the likely major cause of their elevated blood pressure, in an analysis of about 1,000 Americans, which is a much higher prevalence than previously appreciated and a finding that could potentially reorient both screenings for aldosteronism and management for this subset of patients.
“Our findings show a high prevalence of unrecognized yet biochemically overt primary aldosteronism [PA] using current confirmatory diagnostic thresholds. They highlight the inadequacy of the current diagnostic approach that heavily relies on the ARR [aldosterone renin ratio] and, most important, show the existence of a pathologic continuum of nonsuppressible renin-independent aldosterone production that parallels the severity of hypertension,” wrote Jennifer M. Brown, MD, and co-investigators in a report published in Annals of Internal Medicine on May 25. “These findings support the need to redefine primary aldosteronism from a rare and categorical disease to, instead, a common syndrome that manifests across a broad severity spectrum and maybe a primary contributor to hypertension pathogenesis,” they wrote in the report.
The results, showing an underappreciated prevalence of both overt and subtler forms of aldosteronism that link with hypertension, won praise from several experts for the potential of these findings to boost the profile of excess aldosterone as a common and treatable cause of high blood pressure, but opinions on the role for the ARR as a screen to identify affected patients were more mixed.
“ARR is still the best screening approach we have” for identifying people who likely have PA, especially when the ratio threshold for finding patients who need further investigation is reduced from the traditional level of 30 ng/dL to 20 ng/dL, commented Michael Stowasser, MBBS, professor of medicine at the University of Queensland in Brisbane, Australia, and director of the Endocrine Hypertension Research Centre at Greenslopes and Princess Alexandra Hospitals in Brisbane. “I strongly recommend ARR testing in all newly diagnosed hypertensives.”
The study results “showed that PA is much more common than previously perceived, and suggest that perhaps PA in milder forms than we typically recognize contributes more to ‘essential’ hypertension than we previously thought,” said Anand Vaidya, MD, senior author of the report and director of the Center for Adrenal Disorders at Brigham and Women’s Hospital in Boston. The researchers found adjusted PA prevalence rates of 16% among 115 untreated patients with stage 1 hypertension (130-139/80-89 mm Hg), 22% among 203 patients with untreated stage 2 hypertension (at least 140/90 mm Hg), and 22% among 408 patients with treatment-resistant hypertension. All three prevalence rates were based on relatively conservative criteria that included all 726 patients with hypertension in the analysis (which also included 289 normotensive subjects) regardless of whether or not they also had low levels of serum renin. These PA prevalence rates were also based on a “conservative” definition of PA, a level of at least 12 mcg excreted in a 24-hour urine specimen.
When the researchers applied less stringent diagnostic criteria for PA or focused on the types of patients usually at highest risk for PA because of a suppressed renin level, the prevalence rates rose substantially and, in some subgroups, more than doubled. Of the 726 people with hypertension included in the analysis, 452 (62%) had suppressed renin (seated plasma renin activity < 1.0 mcg/L per hour or supine plasma renin activity < 0.6 mcg/L per hour). Within this subgroup of patients with suppressed renin, the adjusted prevalence of PA by the threshold of 24-hour urine aldosterone secretion of at least 12 mcg was 52% in those with treatment-resistant hypertension; among patients with stage 1 or 2 hypertension, the adjusted prevalence rates were just slightly above the rates in the entire study group. But among patients with suppressed renin who were judged to have PA by a more liberal definition of at least 10 mcg in a 24-hour urine sample, the adjusted prevalence rates were 27% among untreated stage 1 hypertensives, 40% among untreated stage 2 patients, and 58% among treatment-resistant patients, the report showed.