Thyroglobulin (Tg) level is used for long-term follow-up of differentiated thyroid cancer (DTC). However, the prognostic value of the postoperative level and the level which can be considered risky are not clear in literature.

To evaluate the prognostic value of postoperative Tg in DTC for subsequent disease-free status. Also, to determine the cutoff with the highest sensitivity and specificity.

A retrospective analysis was performed of 62 patients with non-metastatic DTC presenting to our department from January 2018 to December 2019. Three groups were formed according to postoperative stimulated thyroglobulin (sTg) level: <1ng/ml, 1-5ng/ml, and >5ng/ml. Outcomes were compared at 12 months. ROC curve analysis determined the cutoff with the highest sensitivity and specificity.

Seven the 62 patients showed persistent or recurrent disease at 12 months after diagnosis. Comparing outcomes in the 3 sTg groups showed thyroglobulin to be a significant prognostic variable. A cut-off of 3.15ng/ml had the highest sensitivity and specificity on ROC curve analysis.

Postoperative stimulated thyroglobulin is a useful prognostic tool in the postoperative categorization of patients and can subsequently be tested for its value to guide radioactive iodine therapy.