Endocrine Abstracts (2010) 22 P18

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

GianPaolo Rossi1, Marlena Barisa1, GiovanBattista Desideri2, Claudio Letizia3, Mauro Maccario4, Alberto Morganti5, Gaetana Palumbo6, Anna Patalano7, Anna Realdi1, Elisabetta Roman1, Teresa Maria Seccia1 & Achille Cesare Pessina1

1DMCS, Internal Medicine 4, University of Padova, Padova, Italy; 2Internal Medicine and Public Health, University of L’Aquila, L’Aquila, Italy; 3Internal Medicine, University of Rome, Rome, Italy; 4Endocrinology, University of Turin, Turin, Italy; 5Internal Medicine, University of Milan, Milan, Italy; 6Internal Medicine, Legnano, Italy; 7Endocrinology, University of Padova, Padova, Italy.

The screening for primary aldosteronism (PA) is based on the aldosterone/renin ratio (ARR), which is calculated with the plasma renin activity (PRA) as denominator. A direct measurement of active renin (DRA) is being used as an alternative to PRA, but its diagnostic performance remains uncertain.

Aim of the study was to head-to-head compare the ARR based on PRA (ARR-P) to on DRA (ARR-D), at baseline and post-captopril, for identifying aldosterone-producing adenoma (APA) in a subset (251 patients) of the PAPY Study.

The area (AUC) under the ROC curves was employed for estimating the accuracy of ARR-D and ARR-P for identifying APA and for between tests comparison. PA was found in 13.2% patients, 6.4% of whom had APA and 6.8% idiopathic hyperaldosteronism (IHA); 218 (86.8%) had primary hypertension. The PRA and the DRA showed a weaker correlation at baseline (r=0.26, P<0.0001) and a stronger post-captopril (r=0.65, <0.0001). Both the ARR-D and the ARR-P were useful for identifying APA, as shown by AUC under the ROC curves (0.870±0.058 and 0.973±0.028, respectively) >0.50 (both P<0.0001); at a between-test comparison the ARRs did not differ significantly. For the ARR-D the optimal cut-off value for identifying APA was 27.3, remarkably similar to that previously determined for the ARR-P. Thus, the ARR-D represents a reasonable alternative to the ARR-P for detecting APA.