Evaluation of Elecsys Vitamin D total II

Abstract

The clinical significance of 25-hydroxyvitamin D (25(OH)D), which is the storage form of vitamin D, has attracted attention. In this study, Elecsys Vitamin D total II based on electrochemiluminescence immunoassay was evaluated. The CV of repeatability and the intermediate precision were 2.4 to 5.4% and 4.1 to 10.6%, respectively. The LoQ at which the CV became 20% was 2.69 ng/mL, and the dilution linearity was also good. No effects of interfering substances were observed up to a final concentration. In the analysis of correlation with other methods, the regression equation and correlation coefficient for LIAISON were y = 0.87x + 2.14 and r = 0.94, and those for LUMIPULSE were y = 0.85x + 4.46 and r = 0.97, respectively, indicating a good correlation. However, one sample was outside the 95% confidence interval of the linear regression slope in the correlation between Elecsys and LIAISON. A similar deviation was observed in the same patient sample during the study period, which was considered to be due to differences in the performance of pretreatment reagents that dissociate 25(OH)D from the vitamin D-binding protein (DBP). In the example of the deviation from the high concentration range, the DBP concentration was about 1,000 μg/mL, and the 25(OH)D concentrations measured using Elecsys as a reagent were closest to those obtained by LC-MS/MS. The results of this study indicate that Elecsys is a good reagent with sufficient performance.