Thyroglobulin is a poor predictor of differentiated thyroid cancer in patients who undergo surgery for thyroid nodular diseases.

Objectives: Thyroglobulin, produced exclusively by thyroid follicular cells, serves as a specific tumor marker for the follow-up of differentiated thyroid cancer (DTC) patients after thyroidectomy. However, its role as a predictor of malignancy in patients with thyroid nodules is controversial. We assessed the potential role of preoperative serum thyroglobulin concentration to predict DTC in patients without a preoperative diagnosis of malignancy who underwent partial or total thyroidectomy.

Methods: This retrospective study included patients with a preoperative diagnosis of benign multinodular goiter (MNG) or a thyroid nodule with indeterminate cytology (INC) (Bethesda system categories III/IV) who underwent partial or total thyroidectomy between January 2014 and May 2019. We compared the patients' demographic, clinical, imaging, and biochemical data according to their final diagnosis: DTC or benign thyroid nodular disease. Further statistical analysis included odds ratio calculation and receiver operating characteristic (ROC) curve analysis.

Results: Of 131 patients who met inclusion and exclusion criteria, the indication for surgery was benign MNG in 69 patients and a thyroid nodule with INC in 62 patients. A final diagnosis of DTC was reported in 18 of the 69 benign MNG patients (26%) and in 30 of the 62 thyroid nodule with INC patients (48%). The preoperative measurements of nodule diameter and serum thyroid-stimulating hormone and thyroglobulin concentrations did not significantly differ between patients with a final diagnosis of DTC and those with benign histology.

Conclusions: Preoperative serum thyroglobulin alone is insufficient to differentiate between malignant and benign thyroid nodular disease.