Objective  To investigate the relationship between serum stimulated thyroglobulin(ps-Tg) level and clinicopathological characteristics of patients with differentiated thyroid carcinoma (DTC), and its predictive value for metastasis and reoccurrence.

  Methods  A total of 361 DTC patients were selected, and divided into recurrent and metastatic group(n=38) and non-recurrent and metastatic group(n=323) according to the recurrence and metastasis status during the follow-up period. The relationships between postoperative serum ps-Tg level and the clinicopathological characteristics of DTC patients, between recurrence, metastasis of DTC and postoperative serum ps-Tg level were analyzed. Cox regression model was used to analyze the risk factors for postoperative recurrence and metastasis of DTC patients, and receiver operating characteristic (ROC) was used to analyze the predictive value of serum ps-Tg level for postoperative recurrence and metastasis of DTC patients.

  Results  There were no statistically significant differences in serum ps-Tg levels among the patients with different genders, ages and microcalcifications within the mass(P>0.05). There were statistically significant differences in serum ps-Tg levels among the patients with different tumor location, maximum diameter, the number of lesions, relationship between tumor and thyroid capsule, blood flow in and around mass (P < 0.05). Postoperative serum ps-Tg level in the recurrent and metastatic group was significantly higher than that in the non-recurrent and metastatic group (P < 0.05). Cox regression model analysis showed that higher level of postoperative serum ps-Tg, maximum diameter of 1 cm or more, multifocus, mass and owed clear or not clear of thyroid capsule boundary, richful internal and peripheral blood flow were independent risk factors for DTC patients with cervical lymph node metastasis(P < 0.05). ROC curve showed that optimal cutoff value of serum ps-Tg level for prediction of long-term recurrence and metastasis was 13.60 ng/mL, area under curve (AUC) was 0.743, and 95%CI was ranging from 0.555 to 0.995, and corresponding sensitivity and specificity were 0.711, 0.795, respectively.

  Conclusion  Abnormal increase of serum ps-Tg in patients with DTC mostly indicates poor clinicopathological types, which has a certain predictive value for postoperative recurrence and metastasis in patients.