Application of five frozen human-pooled serum samples assigned by the International Federation of Clinical Chemistry and Laboratory Medicine reference procedure in a traceability investigation of γ-glutamyltransferase catalytic concentration measurements in China

BackgroundThe in vitro directive of the European Union requires traceability to the international recommended reference procedures. The application of the reference procedures is necessary in order to evaluate the accuracy of γ-glutamyltransferase (GGT) assays of routine measurement systems in China.MethodsFive frozen patient-pooled serum samples were assigned values by the International Federation of Clinical Chemistry and Laboratory Medicine (IFCC) reference procedure in order to evaluate the traceability of the results of GGT catalytic activity from six homogeneous systems. One of the serum samples was used to calibrate seven non-homogeneous systems.ResultsAll of the homogeneous systems, except the Dade system (Dade Bering Inc, IL, USA), achieved traceability within the measurement range. The Roche and Hitachi systems were better than the other systems. After calibration, the variance of the non-homogeneous systems decreased dramatically from between 14.50% and 25.23% to between 1.25% and 3.09% and the...