Our findings support US surveillance every 6 months for the first 2 years post-surgery for patients with any of the following: high-risk US features; Tg ≥1.8 ng/mL or rising Tg/TgAb; suspicious/indeterminate US findings; residual thyroid or no RAI; or multi-compartment nodal disease (central + lateral). This evidence concerns the gene TG and thyroiditis.