Post-RIT WBS provides the physician with important information, including the presence of metastatic disease and iodine avidity of residual thyroid tissue.20 As an extremely useful marker of metastasis and relapse, the concentration of serum thyroglobulin, which is synthesized by thyroid follicular cells, is widely used for tumor evaluation after total thyroidectomy for DTC. The gene discussed is TG; the disease is neoplasm.