Longitudinal Change of Postoperative Serum Anti-thyroglobulin Antibody Levels in Patients Without Total Thyroidectomy and Remnant Ablation

Background: There is little information regarding postoperative thyroglobulin antibody (TgAb) changes in patients without a total thyroidectomy and ablation. This study aimed to analyze the longitudinal change of TgAb levels in patients with remnant thyroid.Methods: The study group were patients who had undergone a non-total thyroidectomy for a thyroid tumor from 1996 to 2018. The median follow-up period was 3.5 years (1–7.5 years). Eligible patients had a combined serum Tg and TgAb measurement at least three times biannually. We excluded patients with thyroid dysfunction at the initial diagnosis or with papillary carcinoma who had persistent or any recurrence of disease. Results: A total of 222 patients were enrolled. In the preoperative analysis, 42 (30%) patients had positive TgAb values, and 98 were negative (70%). Seventeen years after the operation, a TgAb value over 1000 IU/ml was not seen. The positive TgAb ratio was stable for 12 years (20%–30%); however, its positivity gradually increased from 13 years onward to 53.8%. The number of patients with consistently negative and positive TgAb values was 151 (68.0%) and 48 (21.6%), respectively. The number of patients with a mixture of positive and negative TgAb values was 10 (4.5%). The number of patients who changed from positive to negative values was six (2.7%) and, inversely, seven (3.2%). Conclusions: We found positivity of TgAb after surgery gradually increases over about 10 years in patients with normal remnant thyroid. We should measure both serum Tg and TgAb values concurrently for the patients with remnant thyroid tissue throughout.