Chemical Pathology, LabPlus, Auckland City Hospital, Auckland, New Zealand.
Biochemistry, Middlemore Hospital Laboratories, Auckland, New Zealand.
Ann Clin Biochem. 2024 Mar;61(2):122-132. doi: 10.1177/00045632231197301. Epub 2023 Sep 2.
Macrotroponin is increasingly recognised as a cause of confusion in interpreting high-sensitivity cardiac troponin (hs-cTnI) results. In this study, we sought to evaluate two practical approaches to detecting macrotroponin. These two approaches are PEG precipitation and SVM (support vector machine) analysis to classify discrepancies between hs-cTn assays.
Residual serum and heparin plasma specimens (n = 483) with initially elevated hs-cTnI from hospital and community laboratories were retested on multiple hs-cTn platforms before and after PEG precipitation and Protein A immunoglobulin depletion. SVM analysis was conducted to identify a linear equation that best discriminated specimens with macrotroponin using a combination of results from two different hs-cTn assays.
The diagnostic performance of PEG precipitation was carried out using Protein A immunoglobulin depletion as the reference comparator. When a cutoff residual activity after PEG precipitation of ≤ 20% was used, this threshold carried a high specificity of 92% (confidence interval 83-98%; n = 189) using the Siemens hs-cTnI Vista assay and 95% specificity (86%-98%; n = 242) using the Abbott hs-cTnI Architect assay. SVM analysis generated a linear equation identifying macrotroponin specimens from results obtained on two hs-cTn assays. This approach can be highly specific, comparable to PEG precipitation when certain assay combinations and concentrations are used.
We describe and identify practical alternatives to detecting macrotroponin. These approaches can be optimised for high specificity, reducing the need for more complex laboratory methods.
巨肌钙蛋白（Macrotroponin）越来越被认为是导致高敏肌钙蛋白（hs-cTnI）检测结果混淆的原因。在这项研究中，我们试图评估两种实用的方法来检测巨肌钙蛋白。这两种方法是 PEG 沉淀和 SVM（支持向量机）分析，用于分类 hs-cTn 检测之间的差异。
从医院和社区实验室最初检测到 hs-cTnI 升高的剩余血清和肝素血浆标本（n = 483），在 PEG 沉淀和 Protein A 免疫球蛋白耗尽前后，在多个 hs-cTn 平台上进行了复测。SVM 分析用于确定最佳的线性方程，该方程使用来自两种不同 hs-cTn 检测结果的组合，来区分存在巨肌钙蛋白的标本。
使用 Protein A 免疫球蛋白耗尽作为参考比较，进行了 PEG 沉淀的诊断性能评估。当使用 PEG 沉淀后残留活性的截值≤20%时，西门子 hs-cTnI Vista 检测的截值具有 92%的高特异性（置信区间 83%-98%；n = 189），雅培 hs-cTnI Architect 检测的截值具有 95%的特异性（86%-98%；n = 242）。SVM 分析生成了一条线性方程，可从两种 hs-cTn 检测结果中识别巨肌钙蛋白标本。当使用某些检测组合和浓度时，这种方法可以具有很高的特异性，与 PEG 沉淀相当。
我们描述并确定了检测巨肌钙蛋白的实用替代方法。这些方法可以针对高特异性进行优化，减少对更复杂的实验室方法的需求。
