Abstract:

Objective To trace the terminal results of gamma-glutamyltransferase （GGT） determination in clinical laboratories to enzymological international system of units through determining GGT trueness control samples assigned the International Federation of Clinical Chemistry and Laboratory Medicine （IFCC） primary reference method,and to achieve the comparability of GGT determination results among clinical laboratories. Methods Four trueness control samples after centrifugation and filtration were transported to clinical laboratories under cold chain,and the samples were determined for 3 d continuously. The trueness control samples were assigned using IFCC primary reference method by Shanghai Center for Clinical Laboratory Enzymological Reference Laboratory,and the target values were obtained. Each sample was not grouped,and the x,s,coefficients of variation （CV） and biases against target values of the 2 samples were evaluated. After each sample was grouped according to instrument brands,the x,s,CV and biases against target values were evaluated as well. Results The results of 82 clinical laboratories showed that the overall CV of the 2 samples were <10%,and the biases against target values were <7.3%. The 82 clinical laboratories were classified into 8 groups according to instrument brands,the within-group CV and biases against target values in Roche,Beckman and Mindray groups were <5.6%. The within-group CV of Beckman,Hitachi and Toshiba groups were <6.4%. The biases of Hitachi and Toshiba groups were >7.2% for A-level sample. The biases for B-level sample was <5.7%. The bias of Beckman group was >30%. The CV of Siemens and Abbott groups were about 10%,and the biases were about 6%. With the target value ±5.5%,the total qualified coincidence rate did not meet the standard of 61%. Conclusions The bias between the results of GGT determination by clinical laboratories tracing back to IFCC reference method and the results assigned using IFCC reference method is small,but the bias of the results of GGT determination by clinical laboratories in Beckman group with IFCC reference method is big.

Key words: Gamma-glutamyltransferase, Trueness verification, Traceability