Reference method applied to assigning values for calibrators in serum gamma-glutamyltransferase assays / 中华检验医学杂志

ABSTRACT

Objective To investigate the efficacy of using a calibrator with values assigned with the reference method for improving the comparability of serum gamma-glutamyltransferase (GGT) measurements.Methods The IFCC reference method for GGT was established and the performance was verified by testing a certified reference material (CRM).A calibrator was prepared and its value for GGT was assigned with the reference method.Forty serum samples were measured on different (including HITACHI 7600,7060,7170,7180 and BECKMAN LX20,OLYMPUS AU 400) chemistry analyzers with Zhongsheng GGT reagent kits calibrated with the calibrator.The samples were also measured on the same analyzers using a theoretical factor.Biases of results obtained with the calibration and with the theoretical factor based calculation were compared.Results The reference method resuhs on the CRM agreed the certified value within the stated uncertainty.Serum results calculated from the theoretical factor showed various biases and inter-analyzer variations.When the analyzers were calibrated with the calibrator,the number of results with biases less than 10% became significantly higher and those with biases more than 20% significantly lower.The variation of the results on 5 serum samples was reduced from 11.0%～14.0% to less than 5% by using the calibrator.Conclusion Accuracy and comparability of GGT measurements with of ZhongSheng GGT kits can be improved by using a calibrator that has a value assigned with the reference method.