Radioactive iodine administered for thyroid remnant ablation following recombinant human thyroid stimulating hormone preparation also has an important adjuvant therapy function.

Background: In December 2007, the USFDA approved recombinant human thyroid stimulating hormone (rhTSH) for radioiodine remnant ablation after total thyroidectomy in patients with well-differentiated thyroid cancer without evidence of metastatic disease. Because previously undetected radioactive iodine (RAI)-avid metastatic lesions can be identified during remnant ablation, we sought to determine if rhTSH-stimulated uptake of RAI into these incidentally discovered metastases is associated with a significant therapeutic (tumoricidal) effect.

Methods: This retrospective review describes the clinical outcome of 84 well-differentiated thyroid cancer patients in whom RAI-avid lesions outside the thyroid bed were first identified at the time of RAI remnant ablation (64 rhTSH stimulated, 20 thyroid hormone withdrawal [THW]) on either the diagnostic (63/84, 75%) or posttherapy (21/84, 25%) whole body scan (76 with locoregional metastasis only and 8 with pulmonary uptake).