Abstract
In patients with suspected primary aldosteronism (PA), the aldosteroneto-renin ratio (ARR) is the most frequently recommended screening test. Further evaluation is based on hormonal changes during volume expansion.
Both analyses are critically dependent on an accurate estimation of renin concentration. Direct active renin (DAR) is a novel laboratory technique used for plasma renin assessment.
The objective of this study was to evaluate DAR for use in PA diagnostic work-ups. The study enrolled 69 healthy volunteers.
Blood sampling was conducted before and after an increase in oral salt intake. Furthermore, a subset of 32 individuals uderwent a saline infusion suppression terst.
DAR and serum aldosterone were measured in all blood samples. To calculate the ARR, serum aldosterone and DAR were expressed in ng/L.
ARR values (median (range); 97,5 percentile) associated with normal and elevated oral salt intake were 8.4 (0.6-37.7); 26.3, and 6.8 (1.1-37.7); 19.6, respectively. DAR and serum aldosterone concentrations (median (range); 97.5 percentile) after saline infusion suppression were 2.9 (2.7-10.7); 7.2 ng/L and 30 (30-72); 54 pmol/L, respectively.
The observed values may be useful in excluding a diagnosis of PA.