Background

Patients with chronic kidney disease often have increased plasma cardiac troponin concentration in the absence of myocardial infarction. Incidence of myocardial infarction is high in this population, and diagnosis, particularly of non ST-segment elevation myocardial infarction (NSTEMI), is challenging. Knowledge of biological variation aids understanding of serial cardiac troponin measurements and could improve interpretation in clinical practice. The National Academy of Clinical Biochemistry (NACB) recommended the use of a 20% reference change value in patients with kidney failure. The aim of this study was to calculate the biological variation of cardiac troponin I and cardiac troponin T in patients with moderate chronic kidney disease (glomerular filtration rate [GFR] 30–59 mL/min/1.73 m²).

Methods and results

Plasma samples were obtained from 20 patients (median GFR 43.0 mL/min/1.73 m²) once a week for four consecutive weeks. Cardiac troponin I (Abbott ARCHITECT® i2000_SR, median 4.3 ng/L, upper 99th percentile of reference population 26.2 ng/L) and cardiac troponin T (Roche Cobas® e601, median 11.8 ng/L, upper 99th percentile of reference population 14 ng/L) were measured in duplicate using high-sensitivity assays. After outlier removal and log transformation, 18 patients’ data were subject to ANOVA, and within-subject (CV_I), between-subject (CV_G) and analytical (CV_A) variation calculated. Variation for cardiac troponin I was 15.0%, 105.6%, 8.3%, respectively, and for cardiac troponin T 7.4%, 78.4%, 3.1%, respectively. Reference change values for increasing and decreasing troponin concentrations were +60%/–38% for cardiac troponin I and +25%/–20% for cardiac troponin T.

Conclusions

The observed reference change value for cardiac troponin T is broadly compatible with the NACB recommendation, but for cardiac troponin I, larger changes are required to define significant change. The incorporation of separate RCVs for cardiac troponin I and cardiac troponin T, and separate RCVs for rising and falling concentrations of cardiac troponin, should be considered when developing guidance for interpretation of sequential cardiac troponin measurements.

中文翻译：

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慢性肾病中心肌肌钙蛋白的生物学变化。

背景

在没有心肌梗塞的情况下，患有慢性肾脏疾病的患者通常血浆血浆肌钙蛋白浓度升高。在这一人群中，心肌梗塞的发病率很高，尤其是非ST段抬高型心肌梗塞（NSTEMI）的诊断具有挑战性。生物学变异的知识有助于理解连续性心肌肌钙蛋白的测定，并可以改善临床实践中的解释。美国国家临床生物化学研究院（NACB）建议在肾衰竭患者中使用20％的参考变化值。这项研究的目的是计算中度慢性肾脏病（肾小球滤过率[GFR] 30-59 mL / min / 1.73 m ²）患者心脏肌钙蛋白I和心肌肌钙蛋白T的生物学变化。

方法与结果

每周一次连续20周从20名患者（中位GFR 43.0 mL / min / 1.73 m ²）获得血浆样品。心肌肌钙蛋白I（AbbottARCHITECT®i2000 _SR，中位数4.3 ng / L，在参考人群中占26.2 ng / L的第99个百分位）和心脏肌钙蛋白T（RocheCobas®e601，中位数11.8 ng / L，在参考人群中的第99个百分位的14） ng / L）使用高灵敏度测定法一式两份进行测量。经过离群值去除和对数转换后，对18例患者的数据进行ANOVA检验，并采用受试者内部（CV _I），受试者间（CV _G）和分析性（CV _A）计算得出的差异。心脏肌钙蛋白I的变异分别为15.0％，105.6％，8.3％，而心脏肌钙蛋白T的变异分别为7.4％，78.4％，3.1％。心肌肌钙蛋白I升高和降低肌钙蛋白浓度的参考变化值分别为+60％/ – 38％和心脏肌钙蛋白T为+25％/ – 20％。

结论

观察到的心肌肌钙蛋白T参考变化值与NACB建议基本兼容，但是对于心肌肌钙蛋白I，需要较大的变化才能定义显着变化。在制定解释顺序性心肌肌钙蛋白测量值的指南时，应考虑将单独的RCV用于心脏肌钙蛋白I和心肌肌钙蛋白T，以及将单独的RCV用于心脏肌钙蛋白浓度的上升和下降。