Blood Sciences, Royal Wolverhampton NHS Trust, Wolverhampton, UK.
School of Medicine and Clinical Practice, University of Wolverhampton, Wolverhampton, UK.
Ann Clin Biochem. 2021 May;58(3):190-195. doi: 10.1177/0004563220987593. Epub 2021 Jan 12.
We compared the effect of haemolysis in sodium measurement using indirect and direct ion-selective electrodes to test the hypothesis that haemolytic effect on sodium would be greater with indirect ion-selective electrode due to electrolyte exclusion effect from released intracellular proteins.
Plasma lithium heparin samples ( = 36) from four volunteers were prepared to give a range of haemolytic indices (H-indices). Samples were analysed for sodium by indirect ion-selective electrode, H-index and total protein on an Abbott Architect c16000 and sodium by direct ion-selective electrode on a Siemens RAPIDPoint 500. Percentage changes in sodium in paired direct and indirect ion-selective electrode values were compared.
Abbott H-index, which represents haemoglobin concentration in g/L, correlated with percentage negative change in sodium by direct ion-selective electrode (ρ 0.995, < 0.001) and indirect ion-selective electrode (ρ 0.991, < 0.001). Percentage negative change was less when sodium was measured by direct ion-selective electrode compared to indirect ion-selective electrode (Wilcoxon signed-rank Z = 3.46, = 0.01). The difference in percentage change in sodium between direct ion-selective electrode and indirect ion-selective electrode correlated with total protein (ρ 0.751, < 0.001). The negative bias in sodium results exceeded the reference change value of 2.2% at an H-index of 8.31 for indirect ion-selective electrode and 9.26 for direct ion-selective electrode.
Haemolysis causes negative influence with sodium measured by both indirect and direct ion-selective electrode due to a dilutional hyponatremia. The additional interference in indirect ion-selective electrode is due to the electrolyte exclusion effect but this is unlikely to be clinically significant as it is small in magnitude.
我们比较了间接和直接离子选择性电极测量钠离子时的溶血效果，以检验这样一个假设，即由于释放的细胞内蛋白质的电解质排除效应，间接离子选择性电极对钠离子的溶血效应更大。
从四名志愿者的血浆肝素锂样本（ = 36）中制备一系列溶血指数（H-index）。使用 Abbott Architect c16000 分析样本的间接离子选择性电极、H-index 和总蛋白以及西门子 RAPIDPoint 500 上的直接离子选择性电极的钠离子。比较直接和间接离子选择性电极值的配对钠离子变化百分比。
Abbott H-index 代表 g/L 中的血红蛋白浓度，与直接离子选择性电极（ρ 0.995， < 0.001）和间接离子选择性电极（ρ 0.991， < 0.001）中钠离子的负变化百分比相关。与间接离子选择性电极相比，直接离子选择性电极测量的钠离子负变化较小（Wilcoxon 符号秩 Z = 3.46， = 0.01）。直接离子选择性电极和间接离子选择性电极之间钠离子变化百分比的差异与总蛋白相关（ρ 0.751， < 0.001）。在 H-index 为 8.31 的间接离子选择性电极和 9.26 的直接离子选择性电极时，溶血导致钠离子出现负偏差，超过了 2.2%的参考变化值。
由于稀释性低钠血症，间接和直接离子选择性电极测量钠离子时都会产生负面影响。间接离子选择性电极的额外干扰是由于电解质排除效应，但由于其幅度较小，不太可能具有临床意义。
