Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Canada.
Department of Clinical Biochemistry, University Health Network, Toronto, Canada.
J Appl Lab Med. 2021 Mar 1;6(2):463-467. doi: 10.1093/jalm/jfaa102.
We observed discordant sodium results from a patient with severe hypernatremia such that whole-blood analysis produced results up to 9.6 mmol/L higher than plasma sodium obtained on the same collection. We investigated this bias by comparing other patients' sodium results and performing comparisons of 3 blood gas and 2 chemistry analyzers.
First, the laboratory information system was queried for whole-blood sodium results >160 mmol/L, which were used for comparison against plasma results from the same collection. Second, whole blood was collected from a healthy donor, a portion of which was spiked with sodium chloride to generate 8 samples with target concentrations of 140 to 185 mmol/L. Whole-blood sodium was measured in duplicate on the ABL90, RAPIDPoint 500, and GEM 4000. Plasma sodium was then measured in duplicate on the Architect c8000 and Cobas c702. Finally, plasma was injected on the blood gas analyzers to measure sodium in singleton.
Overall, 53 paired results from patients showed a significant positive bias on the ABL90 relative to Vitros when sodium was >160 mmol/L. The magnitude of difference was insignificant within the reference range but increased proportionately with concentration. The magnitude and pattern of positive bias in ABL90 sodium results were consistent with the observation in patient results.
In severe hypernatremia, sodium results produced by blood gas and plasma analyzers can differ significantly.
我们观察到一位严重高钠血症患者的钠离子结果不一致，全血分析结果比同一采集的血浆钠离子结果高出 9.6mmol/L。我们通过比较其他患者的钠离子结果并对 3 种血气分析仪和 2 种化学分析仪进行比较来研究这种偏差。
首先，查询实验室信息系统中钠离子结果>160mmol/L 的全血钠离子结果，将其与同一采集的血浆结果进行比较。其次，从健康供体采集全血，其中一部分用氯化钠进行加标，生成 8 个目标浓度为 140 至 185mmol/L 的样本。ABL90、RAPIDPoint 500 和 GEM 4000 上对全血钠离子进行重复测量。然后，在 Architect c8000 和 Cobas c702 上对血浆钠离子进行重复测量。最后，将血浆注入血气分析仪以单独测量钠离子。
总体而言，53 对患者的配对结果显示，当钠离子>160mmol/L 时，ABL90 相对于 Vitros 存在显著正偏差。在参考范围内差异不显著，但随着浓度的增加而成比例增加。ABL90 钠离子结果中阳性偏差的幅度和模式与患者结果中的观察结果一致。
在严重高钠血症中，血气和血浆分析仪产生的钠离子结果可能存在显著差异。
