Performances of a new automated chemilunescence-based immunoassay for aldosterone measurement

Program: Abstracts - Orals, Featured Poster Presentations, and Posters
Session: MON 723-757-Renin-Angiotensin-Aldosterone System/Endocrine Hypertension
Bench to Bedside
Monday, June 17, 2013: 1:45 PM-3:45 PM
Expo Halls ABC (Moscone Center)

Poster Board MON-736
Damien Gruson*1, Dominique M Maiter2 and Thibault Lepoutre3
1Cliniques Universitaires Saint Luc, Brussels, Belgium, 2Univ of Louvain, Brussels, Belgium, 3cliniques universitaires saint luc
Background: Measurement of circulating levels of aldosterone is important for the screening of primary aldosteronism and for the clinical assessment of hypertensive patients. Radio-immunoassays (RIA) remain widely used for the measurement of aldosterone but some automated immunoassays and mass-spectrometry assays are emerging. The aim of our study was to evaluate the performances of a new automated aldosterone immunoassay.

Methods: Limit of detection of the Liaison® aldosterone assay (Diasorin), a fully automated immunoassay with chemiluminescence based detection, was determined with a 10g/L bovine serum albumin solution. Method imprecision was determined with quality control materials and a pool of serum samples. Method comparison was performed with a commercial RIA (coat-a-count®, Siemens) in130 patients samples.

Results: The limit of detection of the automated assay was 0.2 ng/mL. With quality control materials, between-run coefficients of variation (CV) were 10.9% at 5.0 ng/mL (n=16) and 6.0% at 25.6 ng/mL (n=12) with the Liaison® assay. For the serum pool with a concentration of 16.7 ng/mL, close to our laboratory cut-point of 14 ng/mL, the between-run coefficient of variation was 7.2% (n=9). For samples with aldosterone concentrations below 14 ng/mL (n=93), a positive and significant correlation was observed between the two methods (r = 0.89, p<0.0001) and Passing and Bablock regression analysis provides a slope of 1.07 and an intercept of -0.007, without significant deviation of linearity. The mean difference observed on Bland an Altman plot was 0.8 ng/mL.For samples with aldosterone concentrations higher than 14 ng/mL (n=37), a positive and significant correlation was observed between the two methods (r = 0.95, p<0.0001) and Passing and Bablock regression analysis provides a slope of 0.97 and an intercept of 0.41, without significant deviation of linearity. The mean difference observed on Bland an Altman plot was -1.9 ng/mL.

Conclusions: Our study demonstrated satisfactory analytical performances for the Liaison® aldosterone assay and results comparable to those obtained with the radioimmunoassay. Therefore, if our preliminary results are confirmed by larger studies, the Liaison® assay might be relevant for screening of primary aldosteronism and for the assessment of hypertensive patients.

Nothing to Disclose: DG, DMM, TL

*Please take note of The Endocrine Society's News Embargo Policy at http://www.endo-society.org/endo2013/media.cfm