Study on the quantity value transfer of enzymes from the reference measurement system

Abstract

Objective Using the frozen human-pooled serum samples，with values assigned by the enzyme reference procedure in laboratory network to explore the way of quantity value transfer from enzyme reference measurement system to routine ones. Methods The study is about quantity value transfer. The frozen human-pooled serum sample was assigned by the enzyme reference laboratory network including six domestic reference procedure laboratories，namely Beijing Chaoyang Hospital affiliate of Capital University of Medical Sciences, Beijing Aerospace general Hospital, Beijing Shijitan Hospital affiliate of Capital University of Medical Sciences, Peking Union Medical College Hospital, Beijing Leadman Biochemistry Co.,Ltd. and Sichuan Maker Biotechnology Co.,Ltd., which used the reference measurement procedures of creatine kinase (CK) and lactate dehydrogenase (LDH) from the International Federation of Clinical Chemistry and Laboratory Medicine (IFCC) . First, the assigned serum was used to calibrate or verify trueness of routine measurement systems from the 49 laboratories of tertiary hospitals in Beijing in Feb,2013 by Beijing Center for Clinical Laboratories. Second, the assigned serum and two levels of patient samples were tested in duplicate by laboratory's measurement systems after calibration with manufacturer′s calibrator and with assigned serum. During this procedure, all laboratories data were collected. Harmonization of results was observed after calibration with the assigned serum according to the statistics. Results After calibration, the interlaboratory coefficients of variation (CVs) of two patient samples were decreased from 4.67% and 5.96% to 1.86% and 1.47% for CK and from 5.72% and 5.04% to 3.67% and 3.62% for LDH. For peer group of A and B instrument , after calibration, both CVs of the assigned serum and two patient samples were less than 2% for CK, and less than 4% for LDH ; For C instrument group, which was not calibrated with the assigned serum ,the biases were -4.75% for CK and -13.1% for LDH, while the biggest CVs were 3.64% for CK and 7.57% for LDH. For peer group of reagents, after calibration, the CVs were decreased from 1.60%-4.44% to 0.23%-1.62% for CK and from 0.93%-6.07% to 1.06%-2.72% for LDH. Conclusions It is one of the feasible ways for quantity value transfer by using the frozen human-pooled serum samples, which were assigned by the enzyme reference laboratory network for calibration or verification. It can effectively solve the problem of trueness and harmonization of enzyme testing results. In addition, for those measurement systems which are not applicable for this calibration.（Chin J Lab Med，2014,37：110-114） Key words: Enzymes; Clinical chemistry tests; Reference standards; Quality control; Clinical laboratory information systems; International system of units