A role for subtler forms of aldosteronism
Defining PA as at least 12 mcg secreted in a 24-hour urine collection “is relatively arbitrary, and our findings show that it bisects a continuous distribution. How we should redefine PA is also arbitrary, but step one is to recognize that many people have milder forms of PA” that could have an important effect on blood pressure, Dr. Vaidya said in an interview.
Dr. Robert M. Carey
“This is the very first study to show that aldosterone may be contributing to the hypertensive process even though it is not severe enough to be diagnosed as PA according to current criteria,” said Robert M. Carey, MD, a cardiovascular endocrinologist and professor of medicine at the University of Virginia in Charlottesville and a coauthor on the new report. “More patients than we have ever known have an aldosterone component to their hypertension,” Dr. Carey said in an interview.
The new report on the prevalence of unrecognized PA in hypertensive patients “is a game changer,” wrote John W. Funder, MD, professor of medicine at Monash University in Clayton, Australia, in an editorial published along with the new report. In the editorial, he synthesized the new findings with results from prior reports to estimate that excess aldosteronism could play a clinically meaningful role in close to half of patients with hypertension, although Dr. Stowasser called this an “overestimate.” The new results also showed that “the single spot measurement of plasma aldosterone concentration, which clinicians have used for decades to screen for primary aldosteronism, is not merely useless but actually misleading. The authors cautioned readers about the uncertain representativeness of the study population to the U.S. population, but I believe that the findings are generalizable to the United States and elsewhere,” Dr. Funder wrote. “The central problem is that plasma aldosterone concentration is a very poor index of total daily aldosterone secretion. A single morning spot measurement of plasma aldosterone cannot take into account ultradian variation in aldosterone secretion.”
The importance of finding excess aldosterone
Identifying patients with hypertension and PA, as well as hypertensives with excess aldosterone production that may not meet the traditional definition of PA, is especially important because they are excellent candidates for two forms of targeted and very effective treatments that have a reliable and substantial impact on lowering blood pressure in these patients. One treatment is unilateral adrenal gland removal in patients who produce excess aldosterone because of benign adenomas in one adrenal gland, which accounts for “approximately 30%” of patients with PA. “Patients with suspected PA should have an opportunity to find out whether they have a unilateral variety and chance for surgical cure,” said Dr. Stowasser in an interview. “Patients with PA do far better in terms of blood pressure control, prevention of cardiovascular complications, and quality of life if they are treated specifically, either medically or particularly by surgery.”
The specific medical treatment he cited refers to one of the mineralocorticoid receptor antagonist (MRA) drugs, spironolactone and eplerenone (Inspra), because mineralocorticoid receptor blockade directly short-circuits the path by which aldosterone increases blood pressure. “We’re advocating earlier use of MRAs” for hypertensive patients identified with excess aldosterone production, said Dr. Carey. He noted that alternative, nonsteroidal MRAs, such as finerenone, have shown promise for efficacy levels similar to what spironolactone provides but without as many adverse effects because of greater receptor specificity. Finerenone and other nonsteroidal MRAs are all currently investigational. Spironolactone and eplerenone both cause hyperkalemia, although treatment with potassium binding agents can blunt the risk this poses. Spironolactone also causes bothersome adverse effects in men, including impotence and gynecomastia because of its action on androgen receptors, effects that diminished with eplerenone, but eplerenone is not as effective as spironolactone, Dr. Carey said.