天门冬氨酸氨基转移酶“改良参考方法”的建立及其用于测定结果的可比性研究

目的应用不含磷酸吡哆醛的参考方法评价不同实验室间天门冬氨酸氨基转移酶（AST）测定结果的可比性。方法参照国际检验医学溯源联合会（JCTLM）推荐的参考方法及日本临床化学会相关文件,建立不含磷酸吡哆醛的AST参考方法。根据美国临床实验室标准化协会（CLSI）系列文件对该方法的精密度、正确度、线性范围等性能进行评价。应用该参考方法对新鲜血清进行赋值作为校准品校准广州地区10家实验室的常规检测系统,比较校准前、后新鲜血清、能力验证样本以及市售制备物质测定结果间的偏倚,进行检验结果的可比性评价。结果改良参考方法的批内不精密度〈1%,总不精密度〈2%;检测日本临床化学会酶参考品结果均在其不确定度允许范围内,参加参考实验室网络赋值计划测定结果与均值比较在等效限内。改良AST参考方法分析测量范围上限为413.6 U/L。校准前新鲜血清测定结果与参考方法测定结果之间偏倚〉20%的所有11个测定结果中,有10个测定结果来源于用理论K值计算酶活性的检测系统;校准前新鲜血清组最大偏倚为-25.0%,平均偏倚为9.3%;使用改良参考方法定值的酶校准品校准后,最大偏倚降为12.3%,平均偏倚降为2.1%。而能力验证样本和市售制备物中AST测定结果的平均偏倚在校准前后则变化不大,市售制备物组平均偏倚反而略有升高。结论应用参考方法定值的新鲜血清作为校准品进行校准是实现不同检测系统检验结果一致性和可比性的有效途径,非新鲜血清样本存在不同程度的基质效应。

Research on the comparability of AST results by improved reference method

Objective To research the comparability of aspartate aminotransferase（AST） results among different laboratories by a reference method without pyridoxal phosphate. Methods The improved reference method without pyridoxal phosphate for AST was established according to the documents of Jonit Committee for Traceability in Laboratory Medicine（JCTLM） and Clinical Chemistry Society of Japan.The precision,accuracy and linear range were evaluated according to the documents of the Clinical and Laboratory Standards Institute（CLSI）.The improved reference method was used to evaluate the comparability and calibrate the bias of AST results among 10 different laboratories in Guangzhou.The evaluation was performed before and after a calibration by a common serum calibrator that had a value assigned by the reference method.Results For the measurement with improved reference method,the within-run coefficient of variation（CV） was less than 1%,and the total CV was less than 2%.The biases with target values of JC-ERM and network evaluation results all fulfilled the requirements.The upper limit of the AST measurement range of improved reference method was 413.6U/L.Among the 11 testing systems,the bias of AST fresh serum before calibration compared with the reference method was 20%,and 10 were enzyme activity computed with theoretical K value.The maximum bias of AST results of fresh serum before calibration was-25.0%,and the average bias was 9.3%.Calibrated with enzyme calibrator of the improved reference method,the maximum bias decreased to 12.3%,and the average bias was 2.1%.The average bias of AST results of external quality assessment materials and commercial materials showed no significant difference before and after the calibration.Furthermore,the average bias of the commercial materials increased a little after the calibration.Conclusions The traceability of AST measurement can be effectively improved in different testing systems by using a common fresh serum calibrator that has a value assigned by the reference method.There are some matrix effects in non-fresh-serum calibrators.