Inter-platform variability of TgAb, TPOAb and TRAb immunoassays: analytical agreement and consequences for antibody positivity
Qiang You, Yifei Sun, Guoyu Wang, Liu Yang, Chaozhen Jiang, Linbo Ye, Yang Han, Juhua ZhuangAbstract
Objectives
To compare the agreement of anti-thyroglobulin (TgAb), anti-thyroid peroxidase (TPOAb), and thyrotropin receptor antibody (TRAb) results across four automated immunoassay platforms, and to assess the impact of assay variability on positivity rates in different clinical populations.
Methods
A total of 742 serum samples were collected from Shanghai Seventh People’s Hospital between September and December 2025. TgAb, TPOAb, and TRAb levels were measured using four chemiluminescence immunoassay platforms (Roche e 601, Mindray CL-8000i, Abbott Alinity i, and Snibe MAGLUMI X3).
Results
Significant inter-assay variability was observed. Passing–Bablok regression demonstrated proportional differences among platforms, with slopes ranging from 0.1935 to 2.8455 for TgAb, 0.6486 to 2.1930 for TPOAb, and 0.7918 to 1.2698 for TRAb. Bland–Altman analysis revealed wide limits of agreement, particularly for TgAb and TPOAb. TgAb and TPOAb positivity rates were highest in autoimmune thyroiditis, but showed marked inter-platform variation across all disease groups (Cochran’s Q, p<0.001). TRAb positivity was consistently high in Graves’ disease (89.81–98.15 %) and low in other groups (3.00–15.18 %), with relatively better agreement across platforms.
Conclusions
Inter-assay variability exists in thyroid autoantibody measurements, particularly for TgAb, leading to inconsistent positivity rates. Platform-dependent differences may influence interpretation of thyroid autoantibody results and emphasize the need for assay harmonization.