A Retrospective Review of the Effectiveness of Recombinant Human TSH as a Preparation for Radioiodine Thyroid Remnant Ablation

Radioiodine remnant ablation (RRA) is frequently used after a thyroidectomy for differentiated thyroid carcinoma because it has been reported to reduce the number of local recurrences and to increase overall survival. Although the traditional method of preparation for RRA is thyroid hormone withdrawal, several physicians at our medical center have offered the option of having RRA after preparation by recombinant human thyroid-stimulating hormone (thyrotropin; TSH) over the past 2 y. During this same time period, other patients at our center were prepared for RRA by hormone withdrawal. We took this opportunity to retrospectively review the rate of complete remnant ablation in patients having RRA after hormone withdrawal compared with those having RRA after recombinant human TSH. Only patients who had RRA after January 1, 1999, and follow-up diagnostic studies at our medical center, were included in the analysis. A successful ablation was defined as no visible radioiodine uptake on the follow-up diagnostic scans, performed with 185 MBq (5 mCi) (131)I. The 2 groups had comparable patient and tumor characteristics and received similar ablative activities of (131)I. We found that 84% of those prepared by recombinant human TSH, and 81% of those prepared by hormone withdrawal, had complete resolution of visible thyroid bed uptake after RRA (P = not significant). Given the biases that exist in retrospective studies, we cannot yet recommend RRA preparation by recombinant human TSH for routine use. However, these preliminary findings are favorable enough to support the design of a prospective randomized trial comparing RRA success rates after preparation by either thyroid hormone withdrawal or recombinant human TSH.