Effect of Hashimoto thyroiditis on low-dose radioactive-iodine remnant ablation

Background Radioactive-iodine remnant ablation is an integral part of the papillary thyroid carcinoma (PTC) treatment. Although a minimum dose is usually recommended, there is controversy as to whether the low-dose (1100 MBq) radioactive-iodine remnant ablation is adequate for selected patients. Methods A retrospective cohort study was conducted on 691 patients. Patients with no remnant thyroid on the follow-up whole body scan and low stimulated thyroglobulin (sTg) level (<2.0 ng/mL) were deemed as successful treatment cases. Results Initial low-dose radioactive-iodine remnant ablation was successful in 431 patients (62.3%). Multivariate analysis demonstrated a negative correlation between successful radioactive-iodine remnant ablation and coexisting Hashimoto thyroiditis based on histopathology diagnosis (odds ratio [OR] = 3.23; p <.001) as well as elevated preablation sTg (OR = 1.24; p <.001). Conclusion Our data suggest that coexisting Hashimoto thyroiditis and elevated sTg are negative predictive factors for successful low-dose radioactive-iodine remnant ablation treatment. An appropriate risk-adjusted approach may improve the efficacy of radioactive-iodine remnant ablation treatment.