The aldosterone–renin ratio based on the plasma renin activity and the direct renin assay for diagnosing aldosterone-producing adenoma

Background The screening for primary aldosteronism is based on the aldosterone–renin ratio calculated with the plasma renin activity (PRA) value as denominator. A direct measurement of active renin (DRA) is being used as an alternative to PRA, but its diagnostic performance remains unclear. Method We, therefore compared, head-to-head, the aldosterone–renin ratio based on PRA with that based on DRA, at baseline and after captopril administration, for identifying aldosterone-producing adenoma (APA) in 251 patients of the Primary Aldosteronism Prevalence in hYpertension Study (PAPY). The area under the receiver operator characteristics curves was used for estimating the accuracy of the aldosterone–renin ratio based on either renin assay for identifying APA and for the comparison between tests. Results The rate of primary aldosteronism was 13.2%; 6.4% of the patients had an APA and 6.8% idiopathic hyperaldosteronism; 218 (86.8%) had primary hypertension. The area under the receiver operator characteristics curve for identifying APA was higher than 0.50 for the aldosterone–renin ratio based on both renin values (0.870W0.058 for DRA and 0.973W0.028 for PRA) (P<0.0001 for both) and did not differ significantly between the aldosterone–renin ratios calculated with either renin assay. For the aldosterone–renin ratio based on DRA, the optimal cutoff value for identifying APA was 27.3 ng/mIU, remarkably similar to that previously determined for the aldosterone–renin ratio based on PRA. Conclusion Thus, the aldosterone–renin ratio based on DRA is a valuable alternative to that based on PRA for detecting APA.