The Role of Anti-Thyroglobulin Antibodies in Predicting Thyroid Cancers in Patients Undergoing Thyroidectomy

Background: Preoperative prediction of thyroid malignancy can help in risk stratification and perioperative management. It has been debated that anti-thyroglobulin antibody (TgAb) are more frequently elevated in patients with thyroid cancer than in the general population. Aims: to evaluate the predictive value of TgAb in predicting thyroid cancer in patients undergoing thyroidectomy. Patients and Methods: This is a prospective single-center study including 98 patients diagnosed with a thyroid nodule and scheduled to have a thyroidectomy. Demographic data and final histopathology reports were reported. Serum levels of TgAb were measured by ready kit using competitive radioimmunoassay. Accordingly, patients were divided into two groups: TgAb-positive and TgAb-negative groups. Results: Thyroid malignancy was reported in 18 patients (18.37%), while the other 80 patients (81.63%) were found to have benign tumors. Twenty-one patients (21.43%) were TgAb-positive and 77 (78.57%) were TgAb-negative. The frequency of positive TgAbs among patients with thyroid malignancy was 61.11% compared to 12.5% among patients with benign tumors (OR= 11.0, 95%CI= 3.46-34.96, P< 0.001). The sensitivity and specificity of TgAbs were 61.11% and 87.5% respectively. The positive and negative predictive value of TgAbs were 52.38% and 90.91%, respectively Using receiver operating characteristic curve was used to find out the cut off value of TgAb in predicting thyroid malignancy. The area under curve was 0.681, 95%CI= 0.565-0.797, p= 0.048. The sensitivity and specificity of the test at the TgAb cut off value= 114.6 U/ml was 0.35 and 0.77 respectively. Conclusions: Positive preoperative serum TgAb level was associated higher frequency of thyroid malignancy. The TgAb has poor sensitivity (61.11%) and good specificity 87.5%) in predicting thyroid malignancy in patients undergoing thyroidectomy. Keywords: thyroid malignancy, anti-thyroglobulin antibodies, sensitivity and specificit