Changes in serum thyroglobulin and antithyroglobulin shortly following high-intensity focused ablation of benign thyroid nodules in patients with positive antithyroglobulin status

Background: We aimed to describe changes in serum thyroglobulin (Tg) and anti-Tg autoantibody shortly following high-intensity focused ultrasound (HIFU) ablation in patients with positive anti-Tg status by comparing them with patients with negative anti-Tg and to correlate them with 6-month nodule shrinkage and treatment success. Methods: From 2015 to 2017, patients who underwent HIFU ablation of a benign thyroid nodule were analysed. Serum Tg and anti-Tg were checked on treatment day (baseline) and 4 days after treatment. Anti-Tg >99 IU/ml were considered positivity. Percentage Tg or anti-Tg change = [Level on Day-4 - baseline level]/[Baseline level] x 100 while nodule shrinkage was measured by volume reduction ratio (VRR) = [Baseline volume - volume at 6 month]/[Baseline volume] x 100. Treatment success was defined as VRR >50%. Results: Among the 276 eligible patients, 85 (30.8%) patients were positive for anti-Tg (Group I) while the others (n = 191, 69.2%) were negative (Group II). Relative to group II, Group I had a less significant Tg rise on Day 4 (4121.78 +/- 9321.90% vs. 5711.53 +/- 23487.20%, p = .013). There was a fall in anti-Tg on day 4 for group I (-11.56 +/- 139.69%). This percentage anti-Tg drop significantly correlated with the 6-month VRR (rho = -0.602, p = .030) but was not a significant factor of treatment success. Conclusions: Given the fact that the percentage anti-Tg drop correlated significantly with 6-month nodule shrinkage in group I, monitoring early anti-Tg change may help to predict the 6-month nodule shrinkage in patients with positive anti-Tg.