THU589 Positivity Rates Of Screening Criteria For Primary Aldosteronism: A Cohort Comparison Study

Disclosure: M. Marcelli: None. A. Panov: None. C. Bi: None. J.W. Funder: None. M.J. McPhaul: None. Current screening for primary aldosteronism (PA) relies on a single blood draw for plasma aldosterone concentration (PAC) and plasma renin activity (PRA) to establish an aldosterone-to-renin ratio (ARR). However, ARR cutoff levels vary between expert centers. Many studies have demonstrated that PAC may not represent a patient’s actual aldosterone status, suggesting the possible fallibility of the ARR. To investigate this possibility, we compared the positivity rates of 2 indicators of probable PA—ARR>28.9 and suppressed renin (PRA<1 ng/ml/hr)—in a cohort of 38,507 paired PAC and PRA samples. For each indicator, we also assessed positivity rates by self-reported sex (20578 [53.5%] women, 17882 [46.5%] men). Of the cohort, 1623 (4.2%) tested positive for possible PA based on an ARR of 28.9; 19551 (50.8%) tested positive for suppressed renin. Among the latter group, 2585 (6.7%) had PAC>15 ng/dL, 8465 (22%) between 5-15 ng/dL, and 8501 (22.1%) < 5 ng/dL. A recent algorithm suggested by Vaidya (1) defines the first of these groups as overtly positive screening and the second, intermediate group as positive screening, for a total positivity rate of 28.7%. Given the suppressed renin, there are probably a handful of positive PA cases, even in the 22.1 % group with PAC<5 ng/dL. A second finding was that rates of probable PA differed by sex. These differences were minor for the ARR criterion (4.3% of women vs. 4.1% of men tested positive) but major for the suppressed renin criterion with PAC>15 ng/dL (5.7% of women vs. 7.9% of men tested positive) and 5-15 ng/dL (23.6% of women vs. 20.2 of men tested positive). Florid PA was the only condition where more males than females tested positive, a finding deserving further expert consideration and study. In comparing two indicators of probable PA, the ARR criterion yielded a lower positivity rate than the suppressed renin criterion, suggesting that most PA cases may remain undetected if using AAR as a screening test.Reference: (1) JCEM 2020;105:3771 Presentation: Thursday, June 15, 2023