Analysis of the international and domestic RELA results of three enzymes and evaluation of their reference methods

Objective To analyze the results of three enzymes[alanine aminotransferase(ALT),aspartate aminotransferase(AST) and lactate dehydrogenase(LDH)] in the ring trials of Reference Laboratories In Medicine(RELA) organized by International Federation of Clinical Chemistry(IFCC) and the ring trials organized by National Center for Clinical Laboratory(NCCL) in 2006 and 2007,and evaluate the analytic characteristic and reliability of the reference methods of ALT,AST and LDH.Methods ALT,AST,and LDH were measured by the standard operating procedure(SOP) of reference methods published by IFCC,and the combined standard uncertainty was calculated according to Quantifying Uncertainty in Analytical Measurement(QUAM) 2000.The analytic characteristic of the reference methods was evaluated by human enzyme calibrators of Asahi Kasei Pharma corporation from Japanese Committee for Clinical Laboratory Standards(JCCLS).Results The within-laboratory coefficient of variation(CV) of the three enzymes was ranged from 1.5%-2.1% in the 2006 ring trials of RELA organized by IFCC and NCCL,while the within-laboratory CV of the three enzymes was less than 1.1% in the 2007 ring trials,and the bias(%) was less than that in 2006.The values were within the deviation acceptance range except for the values of three samples(7.99%,-7.02%,-13.97%).The within-laboratory CV of ALT,AST and LDH of the human enzyme calibrators of Asahi Kasei Pharma corporation were less than 1%,and the mean value deviation from target values was less than 1%.Conclusions The reference methods for the measurement of catalytic activity of ALT,AST and LDH have been improved and stable in our laboratory,and the results in the 2007 ring trials excelled those in the 2006 ring trials.