[Research on comparison of thyroglobulin autoantibody interference in measurement of thyroglobulin between electrochemiluminescent assay and radioimmunoassay].

This paper is aimed to evaluatethe thyroglobulin autoantibody (TgAb) interference in measurement of thyroglobulin (Tg) between electrochemiluminescent assay (ECLIA) and radioimmunoassay (RIA). Tg and TgAb of 84 sera, including 22 Graves' hyperthyroidism(GD), 24 Hashimoto thyroiditis (HT) and 38 differentiated thyroid carcinomas (DTC), were measured by RIA and ECLIA, respectively. Recovery tests were carried out in 3 groups. The sera samples of the first group were added 3 different amount of Tg calibrator; the sera samples of the second group were diluted 5 times, then 100 ng/ml Tg calibrator was added; the sera samples of the third group were divided into different subgroups depending on TgAb concentration with adding 100 ng/ml Tg calibrator,Tg and TgAb were measured in each dilution by ECLIA and RIA. Recovery rate was calculated. The Tg and TgAb values measured by ECLIA were correlated with that measured by RIA (r = 0.676, P = 0.000; r = 0.677, P = 0.000, respectively). When TgAb concentration increased, the Tg values decreased by ECLIA and increased by RIA. The TgAb values were decreased when sera were diluted, and the Tg values also reduced by RIA and increased by ECLIA. The added different amount of Tg calibrator had not significant influence on Tg recovery rates. When TgAb concentration increased, recovery rates of Tg were decreased by ECLIA and increased by RIA. When sera were diluted, the recovery rates of Tg were increased by ECLIA while decreased by RIA. RIA and ECLIA have good correlation with Tg measurement in 10-400 ng/ml. ECLIA has wider measuring range and higher sensitivity than RIA. RIA and ECLIA have good correlation with TgAb measurement. When TgAb is positive, Tg values are underestimated by ECLIA and overestimated by RIA. When sera are diluted, Tg value and the recovery rate are increasing by ECLIA and decreased by RIA. Recovery test can not efficiently rectify Tg value when TgAb is positive.