Mutual interference between serum thyroglobulin and antithyroglobulin antibody in an automated chemiluminescent immunoassay

Objectives: To investigate the analytical interference between serum Tg and TgAb. Design and methods: Tg and TgAb were measured on an automated chemiluminescent immunoassay system in mixed sera from DTC patients and individual samples spiked with exogenous Tg. Results: Tg and TgAb recoveries in mixed patient samples were inversely correlated with expected TgAb or Tg concentrations, respectively. Impaired TgAb recoveries were also found in 50% (10/20) samples with high Tg in the exogenous recovery tests. Conclusions: Mutual but not equal analytical interference between Tg and TgAb is present and concentration-dependent with interpatient variability.