We aimed to determine factors influencing
lymph node metastasis (LNM) and develop a more effective method to assess preoperative N staging. Overall, data of 2130 patients who underwent
thyroidectomy for
thyroid cancer between 2018 and 2021 were retrospectively analysed. Patients were divided into groups according to pN0, pN1a, and pN1b stages. Pathology was used to analyse the correlation between preoperative
serum marker indicators and LNM. Receiver operating characteristic curves were used to compare the diagnostic value of ultrasound (US) examination alone, serum
thyroglobulin, age, and combined method for LNM. A significant moderate agreement was observed between preoperative US and postoperative pathology for N staging. Between the pN0 and pN1 (pN1a + pN1b) groups, the differences in free
triiodothyronine, anti-
thyroid peroxidase antibody, and serum
thyroglobulin levels were statistically significant. Among the indicators, serum
thyroglobulin was an independent predictor of LNM. The area under the receiver operating characteristic curve was 0.610 for serum
thyroglobulin level for predicting LNM, 0.689 for US alone, and 0.742 for the combined method. Both preoperative US and serum
thyroglobulin level provide a specific value when evaluating the N staging of
thyroid cancer, and the combined method is more valuable in the diagnosis of LNM than US alone.