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

Abstract

Purpose: Compared with chemiluminescence immunoassay (CLIA), the quantification of the plasma aldosterone concentration (PAC) via liquid chromatography-tandem mass spectrometry (LC-MS/MS) yields lower values. The extent to which this difference is exacerbated by a reduced glomerular filtration rate (eGFR) is unclear. Therefore, this study aims to assess the impact of renal insufficiency on PAC as measured by CLIA using LC-MS/MS as the reference method.

Methods: In subjects with a normal or reduced estimated eGFR, the PAC was measured using both LC-MS/MS and two different CLIA kits (Mindray and Liaison).

Results: In total, 383 patients were included in our study. Among them, 71 subjects had eGFRs > 90 (Group one), 79 had eGFRs range from 60 to 89 (Group two), 108 had eGFR range from 30 to 59 (Group three), 51 had eGFRs range from 15 to 29 (Group four), and 74 had eGFRs < 15 (Group five) ml/min per 1.73 m². In all the subjects, PAC as measured by CLIA [68.2 (37.1-122.1) pg/ml for Mindray, 109.0 (68.1-170.0) pg/ml for Liaison] were significantly higher than those measured by LC-MS/MS [47.2 (22.9-88.7) pg/ml]. PAC as measured by CLIA was positively correlated with PAC as measured by LC-MS/MS, but the correlation coefficient gradually decreased as eGFR decreased. Between the LC-MS/MS and Liaison CLIA kits, the difference in PAC values increased with reduced eGFR in groups one through five (76.8 %, 69.2 %, 113.2 %, 152.2 %, and 476.2 % for groups one through five, respectively). However, this difference increased only in Group five with the Mindray CLIA kit (46.4 %, 48.1 %, 45.7 %, 45.0 %, and 74.9 % for groups one through five, respectively).

Conclusion: CLIA progressively overestimated PAC as eGFR decreased, particularly with the Liaison method, indicating the need for caution when interpreting these measurements in patients with impaired renal function. In patients with impaired renal function, LC‒MS/MS measurements for PAC are preferable.

Keywords: Chemiluminescence assays; Liquid chromatography–tandem mass spectrometry; Plasma aldosterone; Renal function.