[Evaluation of interference of thyroglobulin autoantibodies with assay of thyroglobulin using electrochemiluminescent...

Serum thyroglobulin (Tg) is primarily used as a tumor marker to detect the recurrent or persistent disease in patients with differentiated thyroid carcinomas. Unfortunately, the serum Tg measurement is technically challenging and the thyroglobulin autoantibody (TgAb) interference remain the most serious problem limiting the clinical value of serum Tg. The direction and magnitude of the interference are related to the method and the concentration and affinity of the TgAb in the specimen. The objective of this study was to evaluate TgAb's interference with assay of Tg by electrochemiluminescent assay (ECLIA). The Tg and TgAb of 84 sera were measured by the ECLIA. Recovery tests were carried out in 3 groups. 3 different Tg calibrators, 50, 100, 200 ng/ml, respectively, were added into the sera of the first group. The sera of second group were doubly diluted 5 times, and meawhile the Tg and TgAb were measured after each dilution, and then 100 ng/ml Tg calibrator was added into the sera. The sera of third group were divided into different subgroups according to TgAb concentration and then 100 ng/ml Tg calibrators were added. Recovery rate (%) was calculated. Tg value decreased when TgAb concentration increased by ECLIA, TgAb value became lower when sera were diluted, Tg value increased. The added Tg calibrator had not significant influence on Tg value and Recovery rate. Recovery rate was lower when TgAb concentration increased. When sera were diluted, the recovery rate was increased. Tg value were underestimated by TgAb interference. After sera were diluted, Tg value became increasing by ECLIA. The added Tg calibrator had not significantly influence on Tg value and Recovery rate. When sera were diluted, the recovery rate was increased. TgAb concentration had significant influence on Recovery rate. Recovery test can not efficiently rectify Tg value when TgAb was positive.