Establishment and evaluation of the reference methods of alanine aminotransferase and aspartate aminotransferase

Objective To establish the reference methods of alanine aminotransferase(ALT) and aspartate aminotransferase(AST)and evaluate their analytic characteristic.Methods The reference methods were established according to relative documents of International Federation of Clinical Chemistry(IFCC),and the measurement condition was optimized.Furthermore,the precision,accuracy and linearity range of the methods were evaluated according to the evaluation protocols of National Committee for Clinical Laboratory Standards(Document EP5-A2,EP15-A and EP6-A).Results Ultraviolet spectrophotometer,analytic balance,pH meter,electronic thermometer,pipettes and volumetirc flask had been verified and the uncertainty fit to the method′s requirements.When the temperature controller showed 37.2 ℃,the temperature in cuvette showed 37.0 ℃.The temperature in cuvette would reach the set temperature after 180 s.The pipettes application of sample model test showed the precision of suction once and turning twice,and anear tube inner wall was best.The within-run imprecision of ALT and AST reference methods was less than 1%,and the total imprecision was less than 2%.The biases of enzyme reference material(ERM) produced by Japanese Committee for Clinical Laboratory Standards and the samples from external quality control of reference labortories were all within the limit of requirements.The upper limits of the measurement ranges of ALT and AST were 335.8 and 363.6 U/L respectively,which were both higher than those of IFCC reporting.Conclusions The reference methods have been established basically.Most analytic characteristics such as precison,accuracy and linear range were conform to requirements.The established reference methods can be used for clinical research.