TG and Hashimoto thyroiditis: In patients with papillary thyroid carcinoma (PTC) who have negative serum thyroglobulin (Tg) after initial therapy, the risk of structural disease is significantly higher among those with elevated antithyroglobulin antibodies (TgAb) compared to patients without TgAb.1, 2, 3 Other studies suggest that the presence of chronic lymphocytic thyroiditis (CLT) is associated with a lower risk of persistence/recurrence of PTC.4