Indication for radioactive iodine in patients with papillary thyroid carcinoma without apparent disease after total thyroidectomy but with elevated antithyroglobulin antibodies.

Abstract

OBJECTIVE\nTo evaluate a criterion for the selective indication of radioactive iodine (RAI) based on the short-term behavior of antithyroglobulin antibodies (TgAb) in patients with papillary thyroid carcinoma (PTC) who have negative thyroglobulin (Tg) and neck ultrasonography (US) without abnormalities after total thyroidectomy but elevated TgAb.\n\n\nDESIGN\nThis was a prospective study that evaluated 216 patients with low- or intermediate risk PTC who had nonstimulated Tg ≤ 0.2 ng/ml and no US abnormalities but elevated TgAb 3 months after thyroidectomy. RAI was not indicated in patients with negative TgAb or a > 50% reduction in TgAb concentrations 6 months after initial assessment followed by a negative test or an additional reduction (also > 50%) after 12 months.\n\n\nRESULTS\nOnly two of the 114 patients who did not receive RAI developed recurrences; another 108 patients met the criterion of an excellent response to therapy in the last assessment and TgAb persisted in four patients but there was an additional reduction in their concentration during follow-up. Among the 102 patients who received RAI, post-therapy whole-body scanning (RxWBS) detected persistent disease in 8 (8%). Two of the 94 patients without persistent disease on RxWBS developed recurrences. In the last assessment, in the absence of additional treatment, 54/92 patients (58.7%) without structural recurrence had negative TgAb.\n\n\nCONCLUSIONS\nThe indication for RAI can be based on the short-term behavior of TgAb in patients with PTC and elevated TgAb after thyroidectomy who are not high risk and who do not have apparent disease (nonstimulated Tg ≤ 0.2 ng/ml and no US abnormalities). This article is protected by copyright. All rights reserved.