Accuracy evaluation of results of serum α-amylase measured by 11 routine methods according to IFCC reference method

Objective To evaluate the accuracy of measurement values for α-amylase in serum by routine methods.Methods Four commercial reagents for α-amylase were selected to establish 11 α-amylase routine methods in Hitachi 7170 chemical analyzer including 4 approved test systems(A1,B1,C1 and D1) and 7 conventional methods(A2,B2,C2,D2,B3,C3 and D3).The levels of α-amylase in frozen human serum samples covering the range from 40 to 750 U/L were measured simultaneously by using IFCC reference method and 11 routine methods.The accuracy of measurement was evaluated according to the guideline of EP9-A2.The consistency of the results between each routine method and IFCC reference method was analyzed by the improved Bland-Altman semi-graphical method.The accuracies of the measurement results of each routine method were evaluated comprehensively.Results The regression equations of the measurement values between each routine method and IFCC reference method were Y=0.934X+0.886,Y=1.070X-6.249,Y=0.930X+5.388,Y=0.731X-3.574,Y=0.986X+0.996,Y=0.983X-6.195,Y=0.971X+6.957,Y=1.000X-4.649,Y=0.715X-4.648,Y=0.864X+4.821 and Y =0.757X-4.253,respectively.In the equations,X stood for the measurement values of IFCC reference method and Y stood for the measurement values of each routine methods.Eleven routine methods were evaluated by using IFCC reference method as the comparative method.The measurement results of the 4 methods,i.e.,B1,A2,C2 and D2 were reliable.Conclusions Using frozen human serum samples as calibrators should be an excellent solution for the accuracy of α-amylase values measured by routine methods.