Italian researchers recently reported that compared with contemporary radioimmunoassay (RIA) methods, two new fully automated direct immunoassay systems show better reproducibility and require shorter turnaround times and less hands-on staff time. These findings suggest that the new automated assays may be more suitable for monitoring patients with cardiovascular diseases. However, the investigators cautioned that because they found a proportional bias between the new methods, reference ranges for each are needed.

International guidelines recommend screening and diagnosis of primary aldosteronism by using the aldosterone assay. However, RIA methods commonly used to measure aldosterone pose some analytical challenges, including long incubation times, the need to batch samples for cost-effectiveness, relatively short shelf life of radiolabeled reagents, and drawbacks related to the use of radioactive materials. Researchers in Pisa and Vicenza, Italy, assessed the new assays’ analytical performance in the study, “State of the art of aldosterone immunoassays. A multicenter collaborative study on the behalf of the Cardiovascular Biomarkers Study Group of the Italian Section of European Society of Ligand Assay (ELAS) and Società Italiana di Biochimica Clinica (SIBIOC),” published in Clinica Chimica Acta.

The two automated methods—the LIAISON platform by DiaSorin in Saluggia, Italy, and the iSYS platform by IDS Ltd. in Boldon, UK— showed similar analytical performance. The researchers compared the new methods’ performances against two contemporary RIA methods, including the RIA ALDOCTK-2 kit by DiaSorin and the Aldosterone Coat-A-Count by Siemens.

Overall, the iSYS and LIAISON methods had similar analytical performances, with limits of detection of 83.9 and 92.2 pmol/L and limits of quantitation of 104.4 and 111.1 pmol/L, respectively. Although the investigators observed a close linear regression between these methods, they also found a significant proportional bias between the two.