Abstract: Objective  To investigate the clinical value of serum thymidine kinase 1 (STK1),  thyroglobulin (Tg) and thyroid transfer factor 1 (TTF1) in the differential diagnosis of benign and malignant thyroid nodules. Methods  From January 2016 to January 2018, 95 patients with malignant thyroid nodules were  enrolled as malignant nodules group. 45 patients with benign thyroid nodules and 30 healthy subjects were selected in our hospital as benign nodule group and healthy control group. Serum levels of STK1, Tg and TTF1 were detected by enzymelinked immunosorbent assay. The changes of serum STK1, Tg and TTF1 levels in malignant nodules group, benign nodule group and healthy control group, and the relationship between serum STK1, Tg and TTF1 levels and thyroid TNM staging in malignant nodules and the clinical value of serum STK1, Tg and TTF1 levels were observed to identify the clinical value of benign and malignant thyroid nodules.Results  The levels of STK1, Tg and TTF1 in the malignant nodules group were significantly higher than those in the benign nodules group and the healthy control group (P<0.01). The TTF1 level in the benign nodule group was significantly higher than that in the healthy control group (P<0.01), and the levels of STK1 and Tg in the benign nodule group were not significantly different from those in the healthy control group (P>0.05). The levels of serum STK1, Tg and TTF1 in patients with thyroid malignant nodules increased with the increase of tumor stage (P<0.01).Serum STK1 levels in patients with thyroid malignant nodules were positively correlated with Tg (r=0.816, P<0.01) and TTF1 (r=0.753, P<0.01), while Tg levels were positively correlated with TTF1 levels (r=0.687, P<0.01). The combined detection of STK1, Tg and TTF1 was used as the test variable, and the ROC curve was drawn with the occurrence of thyroid malignancy as the state variable. The optimal cutoff value for joint detection in the diagnosis of thyroid malignancy was >0.193, and its sensitivity was 91.6%. The specificity was 92.6%, and the area under the combined detection curve was 0.960, which was significantly better than STK1 (Z=3.031, P<0.01), Tg(Z=4.477, P<0.01) and TTF1 (Z=4.483, P<0.01), and the area under the curve of STK1, Tg and TTF1 was not statistically significant (P>0.05).Conclusion  STK1, Tg and TTF1 are closely related to the malignant degree of malignant thyroid nodules. The combined detection of three markers has high sensitivity and specificity for the differential diagnosis of benign and malignant thyroid nodules.

Key words: thymidine kinase, thyroglobulin, diagnosis, differential , thyroid nodule