Department of Clinical Pharmacology and Toxicology, PathWest Laboratory Medicine, Nedlands, Western Australia 6009, Australia.
School of Medicine and School of Biomedical Sciences, University of Western Australia, Crawley, Western Australia 6009, Australia.
J Anal Toxicol. 2023 Mar 24;47(3):305-310. doi: 10.1093/jat/bkac084.
Phosphatidylethanol (PEth) forms in erythrocyte membranes after alcohol consumption, offering a persisting biomarker, that is measurable in whole blood, washed erythrocytes and dried blood spots. For a predominantly erythrocyte-restricted analyte, erythrocyte concentrations seem to have most validity in patients who are anemic through alcoholism or other pathologies, despite preparation increasing assay complexity. Differences in specimen preparation alter PEth concentrations for the same patient, meaning that criteria for interpreting PEth results should relate to specimen type, presenting a barrier to achieving harmonization. We therefore tested whether erythrocyte PEth might be validly calculated by hematocrit correction of a whole blood PEth measurement. PEth testing primarily serves to distinguish drinkers from non-drinkers. In choosing between specimen types, it is important to compare their utility in separating those two groups. We therefore processed 281 blood samples from 17 non-drinkers and 61 drinkers, to prepare matched whole blood and washed erythrocyte specimens. These were assayed by liquid chromatography-tandem mass spectrometry and compared in identifying alcohol consumption. The erythrocyte PEth concentration in the whole blood specimens was also calculated by correcting whole blood concentration by the specimen's hematocrit, as an alternative to prepare washed erythrocytes. The hematocrit-corrected erythrocyte concentrations were included in these comparisons. Predictably, this work found that sensitivity was consistently better at the lower cut-off of 8 µg/L than at 20 µg/L. Sensitivities were also higher for washed erythrocytes than whole blood, explained by the lower erythrocyte mass in the same volume of whole blood. Hematocrit-corrected whole blood PEth concentrations correlated with erythrocyte concentrations, except for the four highest values, which did not influence comparative sensitivity. Specificity was 100% for washed erythrocytes, whole blood and hematocrit-corrected whole blood at either cut-off because non-drinkers had undetectable PEth. We conclude that hematocrit correction of whole blood PEth concentrations theoretically provides an alternative to the preparation of washed erythrocytes.
乙醇摄入后会在红细胞膜中形成磷脂酰乙醇（PEth），提供一种持久的生物标志物，可在全血、洗涤红细胞和干血斑中测量。对于主要局限于红细胞的分析物，红细胞浓度似乎在因酒精或其他病理原因导致贫血的患者中最具有效性，尽管准备工作会增加分析的复杂性。尽管标本准备的差异会改变同一患者的 PEth 浓度，但解释 PEth 结果的标准应与标本类型相关，这是实现标准化的一个障碍。因此，我们测试了是否可以通过红细胞比容校正全血 PEth 测量值来有效地计算红细胞 PEth。PEth 检测主要用于区分饮酒者和非饮酒者。在选择标本类型时，比较它们在区分这两组人群的效果非常重要。因此，我们处理了 281 份来自 17 名非饮酒者和 61 名饮酒者的血液样本，以准备匹配的全血和洗涤红细胞标本。这些标本通过液相色谱-串联质谱法进行检测，并在识别饮酒方面进行了比较。也通过校正标本的红细胞比容，计算全血标本中红细胞 PEth 浓度，作为制备洗涤红细胞的替代方法。红细胞比容校正后的红细胞浓度也包含在这些比较中。可以预料的是，这项工作发现，在下限 8μg/L 处的灵敏度始终优于 20μg/L。与全血相比，洗涤红细胞的灵敏度也更高，这是由于全血中相同体积的红细胞量较低所致。红细胞比容校正后的全血 PEth 浓度与红细胞浓度相关，除了四个最高值，它们不会影响比较灵敏度。在两个截止值下，非饮酒者的 PEth 均无法检测到，因此洗涤红细胞、全血和红细胞比容校正全血的特异性均为 100%。我们的结论是，理论上，全血 PEth 浓度的红细胞比容校正提供了一种替代洗涤红细胞的方法。
