The ratios of aldosterone / plasma renin activity (ARR) versus aldosterone / direct renin concentration (ADRR)

Abstract

Primary aldosteronism (PA) is estimated to occur in 5-12% of patients with hypertension. Assessment of aldosterone / plasma renin activity (PRA) ratio (ARR) has been used as a screening test in patients suspected of PA. Direct determination of renin (DRC) and calculation of aldosterone / direct renin concentration ratio (ADRR) could be similarly useful for screening patients suspected of PA. The study included 62 patients with indication for evaluation of the renin-angiotensin-aldosterone system and 35 healthy volunteers. In all participants we measured concentrations of serum aldosterone, plasma direct renin, and PRA after a night's rest and again after walking for two hours. The concentrations of aldosterone, direct renin, and PRA were measured by isotopic methods (radioimmunoassay (RIA) / immunoradiometric assay (IRMA)). Correlations of ARR with ADRR in the supine position were r = 0.9162, r(2) = 0.8165 (p < 0.01); and in the up-right position were r = 0.7765, r(2) = 0.9153 (p < 0.01). The cut-off values of ARR and ADRR ≥ 100 presented highest specificity (99%) for the diagnosis of PA; however, quite acceptable specificity and sensitivity (> 80% and 100%, respectively) appeared for the ratios ≥ 30. We suggest that for practical and economic reasons ARR can be replaced by ADRR.

Prospective validation of an automated chemiluminescence-based assay of renin and aldosterone for the work-up of arterial hypertension

“…Accordingly, the replacement of the PRA with the chemi luminescent renin assay has rapidly occurred at many centers in spite of lack of any proof for superiority of the former over the latter in terms of diagnostic accuracy. The available studies mostly investigated the correlation of DRC with DRA [6][7][8][9][10][11]; only one retrospective study vali dated a chemiluminescent assay in PA patients, but did not compare the ARR CL , with the ARR RIA [12].…”

“…These studies, albeit showing that compared to the radioimmunometric methods the DRC assay allowed saving labor time and costs, overall had limitations in that most of them were designed to compare PRA to DRC [6,[8][9][10][11][12], rather than to test the diagnostic accuracy of the aldosteronerenin ratio (ARR) based on DRC (ARR CL ) and the PRAbased ARR (ARR RIA ), for identifying the sub types of primary aldosteronism that can be diagnosed conclusively. Therefore, no such studies followed the STARD recommendations for estimating diagnostic accu racy [13], which dictate that a mandatory step before any novel test can be introduced in clinical practice entails validation using a "gold standard" as reference.…”

“…Several studies have evaluated chemiluminescent assays for measuring the plasma concentration of active renin (DRC) and aldosterone in hypertensive patients [6][7][8][9][10][11]. These studies, albeit showing that compared to the radioimmunometric methods the DRC assay allowed saving labor time and costs, overall had limitations in that most of them were designed to compare PRA to DRC [6,[8][9][10][11][12], rather than to test the diagnostic accuracy of the aldosteronerenin ratio (ARR) based on DRC (ARR CL ) and the PRAbased ARR (ARR RIA ), for identifying the sub types of primary aldosteronism that can be diagnosed conclusively.…”

Novel Approach to Establishing an Aldosterone: Renin Ratio Cutoff for Primary Aldosteronism

“…4 To date, conventional methods used to correlate the 2 have uniformly involved direct head-to-head comparisons, typically in a small numbers of individuals. [5][6][7][8][9][10][11] This approach has many limitations. First, although PRA and DRC are purported to be mathematically correlated, 5-11 their relationship is not entirely linear, especially when renin levels are extremely high or low.…”

“…Such studies are generally small thus limiting their general applicability. [5][6][7][8][9][10][11] Moreover, the Endocrine Society has advised that the correlation between PRA and DRC is poor at lower renin levels, the domain of greatest importance for PA screening. 1 Indeed, differences in analytical method can result in as much as a 2-fold variation in ARR cutoffs and classification error.…”