Abstract: Background and purpose: Thyroglobulin antibody (TgAb) is often positive in papillary thyroid carcinoma (PTC) patients. This study aimed to investigate the effect of TgAb on radioiodine ablation efficacy in PTC patients. Methods: A total number of 329 PTC patients with no distant metastasis were included and classified into 2 groups ［G1 group (>115 U/mL，n=84) and G2 group (<115 U/mL, n=245)］, G2 group was further divided into 2 subgroups ［S1 (>40 U/mL, n=31) and S2 (<40 U/mL, n=214)］, before ¹³¹I ablation. The median follow-up time was 24 months after a total or subtotal thyroidectomy and subsequent ¹³¹I ablation. The efficacy in terms of ¹³¹I ablation success rates (IBR) between two groups were compared and the influencing factors were analyzed according to criteria posed by 2015 American Thyroid Association Guidelines, then the effect of ¹³¹I dose on IBR was also explored. Results: Female and younger age were more prevalent in patients with high TgAb (P<0.05). The G1 group presented lower IBR over the G2 group (35.7% vs 72.7%, P=0.000). Moreover, S1 group also presented lower IBR over S2 group (54.8% vs 75.2%, P=0.017), indicating the adverse effect from high titer TgAb on IBR. No matter high or low dose, the G1 group presented lower IBR (34.1% vs 71.9%, 37.2% vs 73.2%; P=0.000). However, IBR did not differ in G1 or G2 group either with high or low dose ¹³¹I (P>0.05). TgAb was the only adverse indicator correlating with IBR in multi-logistic regression analysis (P=0.018). Conclusion: TgAb could negatively affect ¹³¹I ablation efficacy, while increasing the dose of ¹³¹I failed to improve the success rate in such cases.

Key words: Papillary thyroid carcinoma, Thyroglobulin antibody, ¹³¹I ablation, Efficacy