Postoperative s-Tg measurements are affected by numerous factors, including the extent of remaining thyroid cancer or normal thyroid tissue, serum thyroid-stimulating hormone concentrations, the analytic sensitivity of the s-Tg detection method, selected s-Tg threshold values, individual patient risk for radioactive iodine-avid local or distant metastasis, interval time from total thyroidectomy, and the diagnostic sensitivity of posttherapy imaging modalities (10). This evidence concerns the gene TG and thyroid gland carcinoma.