Clinical value of serum TgAb test in patients with differentiated thyroid carcinoma coexistent with Hashimoto thyroiditis

Objective: To analyze the prognosis of patients with positive serum thyroglobulin antibody (TgAb) in the papillary thyroid carcinoma (DTC) coexistent with Hashimoto's thyroiditis (HT) after thyroidectomy + ¹³¹I ablation and observe the change in TgAb and its association with the prognosis. Methods: A retrospective analysis was performed on 141 patients with DTC possessing positive serum TgAb (> 115 IU/mL) that were admitted to our hospital from May 2013 to October 2016 after surgical + ¹³¹I treatment, including 14 males and 127 females aged 15-74 (40.86 ± 11.21). Patients were divided into DTC with HT (G1 group, n = 49) and DTC without HT groups (G2 group, n = 92) according to the presence of concurrent HT or not. The disease duration or recurrence rates between the two groups were compared. The changes in TgAb level and its relationship with prognosis were also analyzed. The median follow-up of patients with DTC was 22 months (12-56 months). Prognostic assessment and TgAb trend analysis between the two groups were performed by x² test or Fisher exact probability method. The difference in TgAb levels between different groups was tested by MannWhitney U rank sum test. Results: The age of the patients in the G1 group was lower than that in the G2 group, and the difference was statistically significant. Other clinical and pathological data were statistically in significant. The disease duration or recurrence rate in patients in the G1 group (3/49, 6.12%) was significantly lower than that in the G2 group (20/92, 21.74%, x² = 5.712, P = 0.017). The TgAb proportion showed a declining trend before and after surgery + ¹³¹I in the G1 group (46/49, 93.88%), which was significantly higher than that in G2 group (60/92, 65.22%, x² = 14.073, P < 0.001). In the G1 group, the disease persistence or recurrence rate of TgAb level decreased (1/46, 2.17%) was lower than that of TgAb sustained or increased (2/3, 66.67%, Fisher's test P = 0.008). The disease persistence or recurrence rate of TgAb decreased in the patients in the the G2 group (4/60, 6.67%) and was lower than that of TgAb sustained or increased (16/32, 50.00%, x² = 23.034, P = 0.000). The TgAb value level of preoperative, and the changes in values and rates of TgAb before and after thyroidectomy + ¹³¹I ablation in the G1 group (558.70 IU/mL, 398.09 IU/mL, and 85.15%) were greater than those in the G2 group (352.35 IU/mL, 124.84 IU/mL, and 41.43%), and the differences were statistically significant (U = 1581.00, 1210.00 and 1113.00, all P < 0.05). Conclusion: Among the patients with DTC having positive serum TgAb after thyroidectomy + ¹³¹I ablation, the patients with coexisted HT had improved prognosis, and the change in trend of TgAb can be used as an indicator in monitoring the prognosis of patients with DTC. (authors)