Application of reference methods suggested by IFCC and analysis of the 2006 ring trial results

Abstract

Objective To establish reference methods for the measurement of catalytic activity concentrations of enzymes at 37℃ which have been published by IFCC and evaluate accuracy of reference methods.Methods Six reference methods for the measurement of catalytic activity of enzymes were established with two sets of apparatus systems of PE and Agilent according to International Federation of Clinical Chemistry(IFCC)37℃ reference procedures in two reference labs respectively.The commercial Roche calibrator c.f.a.s was used to monitor the precision of two reference labs as quality control material.Certified Reference Materials(CRMs)represented an efficient tool to assess the analytic performance for the verification of trueness and in two labs.The measurement accuracy of the assays for catalytic activity concentrations of 6 enzymes [alanine aminotransferase(ALT),aspartate aminotransferase(AST),lactate dehydrogenase(LDH),creatine kinase(CK),gamma-glutamyhransferase(GGT),amylase(AMY)]was further verified and validated by international ring trial program.Results The within-laboratory variations of 6 enzymes in both of the reference lab were ranged from 0.5%-1.9%.Their results showed fully agreement with deviation less than 2.1%.The value of CRM was in the tolerant limit and analytic accuracy was verified.The results of four enzymes(ALT,AST,GGT,AMY)lay within (x)±s.However,the result of CK and LDH lay within (x)±2s.Except sample A for the LDH testing,we did not find any deviation variable in the detection of other enzymes.Conclusions The reference methods for the measurement of catalytic activity of enzymes(ALT,AST,LDH,CK,GGT,AMY)at 37℃ in the two labs by use of two sets of apparatus systems of PE and Agilent have been established and these methods showed excellent stability and accuracy. Key words: Enzyme tests; Laboratory techniques and procedures; Reference values; International normalized ratio