Abstract:

Objective To analyze the diagnostic value of serum thyroglobulin (Tg) and antithyroglobulin antibody (TgAb) levels for patients with differentiated thyroid carcinoma (DTC) complicated with Hashimoto's thyroiditis (HT) after the operation and ¹³¹I treatment and to determine corresponding cutoff values. Methods A total of 164 patients with DTC complicated with HT underwent the ¹³¹I treatment after the operation and were followed up for three years. Patients were divided into the recurrence/metastasis group and non-recurrence/metastasis group. The receiver operating characteristic (ROC) curve analysis was conducted to analyze cutoff values of Tg and TgAb for predicting the metastasis for patients with DTC complicated with HT. Results The cutoff values of Tg and TgAb for predicting the metastasis were 1.48 μg/L (with sensitivity of 72.13% and specificity of 98.06%) and 45 kIU/L (with sensitivity of 48.53% and specificity of 100%) according to the ROC analysis. The AUCs of Tg and TgAb were 0.907 and 0.650, respectively. The scatter diagram plotted by measurements of Tg and TgAb of the recurrence/metastasis group was rectangular hyperbola for all patients with DTC complicated with HT. Conclusion For patients with DTC complicated with HT, the cutoff values of Tg and TgAb for predicting the metastasis were 1.48 μg/L and 45 kIU/L according to the ROC curves. Based on the sensitivity, specificity, and AUC, the diagnostic value of Tg was higher than that of TgAb for predicting the metastasis of thyroid carcinoma. Besides, Tg measurements were significantly and negatively correlated to TgAb measurements in the scatter diagram.

Key words: thyroid carcinoma, Hashimoto thyroiditis, thyroglobulin, antithyroglobulin antibody