Christenson Robert H, Duh Show Hong, Apple Fred S, Bodor Geza S, Bunk David M, Panteghini Mauro, Welch Michael J, Wu Alan H B, Kahn Stephen E
Department of Pathology, University of Maryland School of Medicine, Baltimore, MD 21201, USA.
Clin Chem. 2006 Sep;52(9):1685-92. doi: 10.1373/clinchem.2006.068437. Epub 2006 Jul 20.
Cardiac tropoin I (cTnI) measurements show an approximately 20- to 40-fold difference between assays, and better standardization and harmonization are needed. Toward this goal, the AACC cTnI Standardization Committee collaborated with the National Institute of Standards and Technology (NIST) in an earlier study to select 2 candidate reference materials (cRMs).
Two troponin cRMs, a troponin C-troponin I-troponin T (CIT) complex from human heart tissue and a CIT complex from recombinant technology, were supplied to NIST for assessment of composition and purity, and cTnI value assignment. These cRMs and 6 cTnI-positive human serum pools were shipped to manufacturers of 15 cTnI assays. Commutability of the materials was examined by determining the numerical relationship for the cRM preparations between each manufacturer-specified field method and each of the other 14 field methods. These relationships were then compared with the corresponding numerical relationships for the human serum pools. Harmonization of methods was accomplished by determining regression parameters relative to the analytical system yielding values closest to the median for each serum pool. These regression parameters were used to recalculate pool values to harmonize the assays. Interassay CVs before and after harmonization were determined.
Characterization of the CIT and CI cRMs showed that these materials were of specified composition. The proportion of cTnI methods that demonstrated commutability for the CIT cRM was 45%; for the CI cRM, 39% of methods demonstrated commutability. Interassay cTnI variability for the field methods ranged from 82% to 97%, median 88%. After harmonization, variability of the serum pools for the cTnI methods was decreased to between 9.0% and 23%, median 15.5%.
The proportion of methods demonstrating commutability was too low for use as a common calibrator for the cTnI field methods. However a simple strategy using serum pools can improve harmonization of field cTnI methods by more than 5-fold. The CIT cRM was selected by the AACC cTnI standardization committee, and a new lot has been classified as the cTnI certified reference material Standard Reference Material 2921 by NIST.
心肌肌钙蛋白I（cTnI）检测结果在不同检测方法间存在约20至40倍的差异，因此需要更好的标准化和协调统一。为实现这一目标，美国临床化学协会（AACC）cTnI标准化委员会在早期研究中与美国国家标准与技术研究院（NIST）合作，挑选了2种候选参考物质（cRM）。
将两种肌钙蛋白cRM，即来自人心脏组织的肌钙蛋白C - 肌钙蛋白I - 肌钙蛋白T（CIT）复合物和通过重组技术获得的CIT复合物，提供给NIST，用于成分和纯度评估以及cTnI值赋值。这些cRM和6个cTnI阳性人血清混合样本被运送给15种cTnI检测方法的制造商。通过确定每种制造商指定的现场方法与其他14种现场方法中cRM制剂的数值关系，来检验材料的互换性。然后将这些关系与人类血清混合样本的相应数值关系进行比较。通过确定相对于分析系统的回归参数来实现方法的协调统一，该分析系统产生的值最接近每个血清混合样本的中位数。这些回归参数用于重新计算混合样本的值，以协调检测方法。测定协调前后的批间变异系数（CV）。
对CIT和CI cRM的特性表征表明这些物质具有特定的成分。对于CIT cRM，显示出互换性的cTnI方法比例为45%；对于CI cRM，39%的方法显示出互换性。现场方法的cTnI批间变异范围为82%至97%，中位数为88%。协调后，cTnI方法的血清混合样本变异降至9.0%至23%之间，中位数为15.5%。
显示出互换性的方法比例过低，无法用作cTnI现场方法的通用校准物。然而，使用血清混合样本的简单策略可将现场cTnI方法的协调统一提高5倍以上。CIT cRM被AACC cTnI标准化委员会选中，新批次已被NIST列为cTnI认证参考物质标准参考物质2921。
