Results of comparison of the evaluated LC-MS/MS method with LC-MS/MS method of the University of Washington (12) using (A) Tg-AAb negative (n=21), (B) Tg-AAb positive samples (n=29), and (C) comparison with Access™ analyzer (Beckman Coulter) using Tg-AAb positive samples (samples corresponding to the results shown on pane B). A: LC-MS/MSUW=1.17* LC-MS/MSeval. −1.81, r=0.951, Sy,x=8.14; B: LC-MS/MSUW=1.23*LC-MS/MS eval. + 0.15, r=0.917, Sy,x=0.475.)