Comparison of chemiluminescence immunoassay with LC-MS/MS in the determination of plasma aldosterone concentration in patients with declined renal function

Abstract Purpose Compared with chemiluminescence immunoassay (CLIA), quantification of plasma aldosterone concentration (PAC) by liquid chromatography-tandem mass spectrometry (LC-MS/MS) yields lower values. Whether this difference is exacerbated by a declined glomerular filtration rate (eGFR) is unclear. Therefore, this study aims to assess the impact of renal insufficiency on PAC measured by CLIA using LC-MS/MS as the reference method. Methods In subjects with normal or declined estimated glomerular filtration rate (eGFR), PAC were measured by both LC-MS/MS and two different CLIA kits (Mindray and Diasorin). Results 383 patients were included in our study. Among them, there were 71 subjects with eGFR > 90 (group one), 79 with eGFR 60–89 (group two), 108 with eGFR 30–59 (group three), 51 with eGFR 15–29 (group four), and 74 with eGFR < 15 (group five) ml/min per 1.73m2, respectively. In all subjects, PAC measured by CLIA [68.2(37.1-122.1) pg/ml for Mindray, 109.0(68.1–170.0) pg/ml for Diasorin] were significantly increased compared with those measured by LC-MS/MS [47.2(22.9–88.7) pg/ml]. The PAC measured by CLIA was positively correlated with that by LC-MS/MS, but the correlation coefficient diminished gradually with eGFR decline. Between LC-MS/MS and Diasorin CLIA kit, the difference of PAC increased with declined eGFR in groups one to five (76.8%, 69.2%, 113.2%, 152.2% and 476.2% for groups one to five, respectively). However, the difference increased only in group five in Mindray CLIA kit (46.4%, 48.1%, 45.7%, 45.0% and 74.9% for group one to five, respectively). Conclusion In patients with declined renal function, PAC measured by CLIA might be overestimated. Caution is needed in the interpretation of PAC in patients with severe renal impairment. When accurate measurements are required, LC-MS/MS should be considered.