Evaluation of Therapeutic Effect with Serum Thyroglobulin and Whole Body Scan after 200mCi $^{131}I$ Treatment in Patients with Well-Differentiated Thyroid Carcinoma

Thirty-eight patients with metastatic well-differentiated thyroid carcinoma treated with 200mCi were studied. There were false negative serum thyroglobulin values during TSH suppression or at anti-thyroglobulin antibody(+) and discrepancies between findings of whole body scan and serum thyroglobulin level. After one to five cycles of 200mCi therapy, complete remission and partial remission were achieved at 5.3% and 57.9%, respectively. We concluded that all of serum thyroglobulin, TSH, anti-thyroglobulin antibody, or whole body scan were necessary in follow up of metastatic well-differentiated thyroid carcinoma. Also, if there was no response after repetitive 200mCi therapy, higher doses of therapy should be considered.