Predictors of thyroglobulin in the lymph nodes recurrence of papillary thyroid carcinoma undergoing total thyroidectomy

BACKGROUND: To investigate the association between postoperative lymph nodes (LNs) recurrence and distinct serum thyroglobulin (Tg) levels in patients with papillary thyroid carcinoma (PTC). METHODS: This study included PTC patients who underwent total thyroidectomy (TT) with at least central neck dissection and then re-operated due to recurrence of LNs between January 2013 and June 2018. These patients were grouped by negative or positive serum Tg levels according to the American Thyroid Association guidelines. RESULTS: Of the 60 included patients, 49 underwent radioactive iodine (RAI) treatment. Maximum unstimulated Tg (uTg) ≥ 0.2 ng/mL were associated with larger diameter of recurrent LNs (P = 0.027), and higher rate of metastatic LNs (P < 0.001). Serum-stimulated Tg (off-Tg) ≥ 1 ng/mL (P = 0.047) and unstimulated Tg (on-Tg) ≥ 0.2 ng/Ml (P = 0.013) were associated with larger diameter of recurrent LNs. Number of metastatic LNs ≥ 8 was an independent predictor for postoperative maximum uTg ≥ 0.2 ng/mL (OR = 8.767; 95% CI = 1.392–55.216; P = 0.021). Ratio of metastatic LNs ≥ 25% was an independent predictor for off-Tg ≥ 1 ng/mL (OR = 20.997; 95% CI = 1.649–267.384; P = 0.019). CONCLUSION: Postoperative Tg-positive status was associated with larger size of recurrent LNs. Number of metastatic LNs ≥ 8 and ratio of metastatic LNs ≥ 25% were independent predicators for uTg-positive and off-Tg-positive status, respectively.