Abstract
The transition from radioimmunoassay (RIA) to chemiluminescent enzyme immunoassay (CLEIA) for plasma aldosterone concentration (PAC) assays has raised concerns over its impact on primary aldosteronism (PA) diagnosis. This study investigated the correlation between PAC and renin values using RIA, CLEIA, and liquid chromatography/mass spectrometry/mass spectrometry (LC-MS/MS), established cutoff values for PA diagnosis using the aldosterone-to-renin ratio (ARR) with PAC_CLEIA, and assessed the differences in PAC values by measuring weak mineralocorticoids (WMs). This retrospective study evaluated 312 serum PAC samples using RIA, CLEIA, and LC-MS/MS, and analyzed 315 plasma renin samples. Method correlations were assessed through Passing-Bablok regression. Receiver operating characteristic curves determined ARR cutoffs for PA diagnosis. WMs were quantified to evaluate their impact on ΔPAC (RIA-LC-MS/MS) through multiple regression analysis. PAC_CLEIA and PAC_LC-MS/MS values were highly correlated. ARRs derived from PAC_RIAs demonstrated more false positives and lower specificity than ARRs using PAC_CLEIA or PAC_LC-MS/MS. WMs significantly influenced ΔPAC in both the PA and non-PA groups. ARRs using PAC_CLEIA are valuable for determining PA cutoffs in clinical practice. The transition to PAC using CLEIA may enhance PA detection rates. WMs were found to interfere with PAC measurements in the RIA method, affecting outcomes.