Mutual interference between serum thyroglobulin and anti-thyroglbulin antibody in chemiluminescent immunoassay

Objective To investigate the mutual interference between serum thyroglobulin(Tg) and anti-thyroglbulinantibody(TgAb) in chemiluminescent immunoassay(CLIA). Methods Serum Tg and TgAb were measured by automated CLIA.Tg or TgAb recoveries were determined in serum samples blended with sera of different concentrations of TgAb or Tg. Results Tg recovery rate was 93%-112% in low TgAb sera,17%-40% in high TgAb sera with negative correlation with TgAb concentrations (r_s=-0.877,P=0.001),while TgAb recovery rate was 76%-108% in low Tg sera,66%-98% in high Tg sera with negative correlation with Tg concentrations (r_s=-0.881,P=0.004). Conclusions Mutual but not equal interferences between serum Tg and TgAb are present in CLIA,resulting in falsely low concentration in a concentration-dependent manner;TgAb interference existes even at low level and Tg interference existes only at high level.