Postoperative thyroglobulin and neck ultrasound in the risk restratification and decision to perform ¹³¹l ablation

Context: There is much debate surrounding the choice of which patient should be submitted to postsurgical remnant radioiodine remnant ablation (RRA), particularly in low-risk (LR) and intermediate-risk (IR) differentiated thyroid cancer (DTC). Objective: The aim of this study was to evaluate the role of postoperative high-sensitive thyroglobulin (Tg) on L-thyroxine (LT4-HSTg) and postoperative neck ultrasound (US) in risk restratification and decision to perform RRA. Patients: We evaluated 505 patients with LR or IR DTC 3 to 4 months after total thyroidectomy (TTx). All patients underwent RRA and a posttherapeutic whole body scan (ptWBS). Results: After TTx, 29.7%DTC patients had LT4-HSTg ,0.1 ng/mL (Group A) and could be restratified as cured: 1 of 150 had lymph node metastases (LN mets) detected by neck US but negative at ptWBS. 56.8% DTC patients had LT4-HSTg between 0.1 and #1 ng/mL (Group B) and could be restratified either as cured or not cured. In this group, 15 of 287 (5.2%) hadmetastases but only 7were detected by ptWBS; 13.5%DTC patients had LT4-HSTg .1 ng/mL (Group C) and could not be considered as cured by definition. LN mets were present in 11 of 68(16.2%) cases, all detected by neck US. No correlation was found with the presence of metastases and serum LT4-HSTg values or with the level of risk. Conclusions: LT4-HSTg measured 3 to 4 months after TTx is important in the risk restratification of DTC patients but is less relevant than neck US in the decision to perform RRA.