Department of Clinical Pharmacology and Toxicology, PathWest Laboratory Medicine, Nedlands, Western Australia.
Chemical Pathology, NSW Health Pathology, Royal Prince Alfred Hospital, Camperdown, New South Wales, Australia.
Drug Test Anal. 2024 Mar;16(3):251-258. doi: 10.1002/dta.3537. Epub 2023 Jul 4.
Phosphatidylethanol (PEth) is a non-oxidative metabolite of alcohol (ethanol), which is a sensitive and specific indicator of historic ethanol consumption. Although PEth production from ethanol is catalysed by the ubiquitous enzyme phospholipase D, it resides mainly within the erythrocyte compartment of the blood. PEth analysis has been reported in different preparations of whole blood, representing one of the barriers of inter-laboratory comparisons. We previously reported that expressing PEth concentrations in terms of blood erythrocyte content is more sensitive than whole blood volume, and haematocrit-corrected liquid whole blood calculations of erythrocyte PEth and isolated erythrocyte PEth concentrations are comparable when assayed under identical analytical conditions. Acceptance of a clinical diagnostic assay by accreditation bodies requires proficiency testing with a third-party analytical facility. To explore different blood preparations within the same inter-laboratory program, 60 matched isolated erythrocyte or liquid whole blood specimens were tested at three laboratories. Laboratories measured PEth by liquid chromatography-tandem mass spectrometry (LC-MS/MS), two using isolated erythrocytes, while the third used liquid whole blood, which underwent haematocrit correction before comparison with isolated erythrocyte PEth concentrations. There was acceptable consensus (87%) among laboratories to detect PEth around a cut-off of 35 μg/L of erythrocytes. Each laboratory correlated well with the group average PEth concentration (R > 0.98) for each specimen above the cut-off. Differences were observed between laboratories in bias, which did not affect comparable sensitivity at the selected cut-off. This work demonstrates the feasibility of an inter-laboratory comparison for erythrocyte PEth analysis across different LC-MS/MS methodologies and different blood preparations.
磷脂酰乙醇（PEth）是酒精（乙醇）的非氧化代谢物，是历史饮酒量的敏感和特异性指标。虽然乙醇的 PEth 生成是由普遍存在的酶磷脂酶 D 催化的，但它主要存在于血液的红细胞部分。PEth 分析已在全血的不同制剂中报告，这是实验室间比较的障碍之一。我们之前报道过，以血液红细胞含量表示 PEth 浓度比全血体积更敏感，并且在相同的分析条件下测定时，红细胞 PEth 的血细胞比容校正的全血和分离的红细胞 PEth 浓度的计算结果是可比的。认证机构对临床诊断检测的认可需要通过第三方分析机构进行能力验证。为了在同一实验室间方案内探索不同的血液制剂，在三个实验室中测试了 60 个匹配的分离红细胞或全血样本。实验室通过液相色谱-串联质谱法（LC-MS/MS）测量 PEth，其中两个实验室使用分离的红细胞，而第三个实验室使用全血，在与分离的红细胞 PEth 浓度进行比较之前，全血经历了血细胞比容校正。在检测红细胞 35μg/L 左右的截止值时，实验室之间有可接受的一致性（87%）。每个实验室都与每个标本高于截止值的组平均 PEth 浓度（R>0.98）很好地相关。在选择的截止值下，实验室之间观察到差异在偏倚方面，这不会影响可比的灵敏度。这项工作证明了在不同的 LC-MS/MS 方法学和不同的血液制剂之间进行红细胞 PEth 分析的实验室间比较是可行的。
