Success Rate of Radioactive Iodine Therapy in Graves’ Disease Using Dose Corrected for Thyroid Gland Size

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Peerapon Kiatkittikul
Yutapong Raruenrom
Daris Theerakulpisut
Charoonsak Somboonporn


Objective: Dose corrected for thyroid gland size is one of the methods used to determine I-131 activity for patients with Graves’ disease. This study was aimed to find the success rate of this method and the predictors for successful I-131 treatment.
Methods: This retrospective descriptive study was conducted in patients with Graves’ disease who received the first dose of radioactive iodine (RAI) therapy. Patients received a fixed RAI dose of either 10, 15, 20, 25, or 30 mCi for corresponding thyroid gland size of ≤ 50, 51-100, 101-150, 151-200, and >200 grams, respectively. The treatment outcome was assessed 6 to 9 months after the therapy based on serum free thyroxine and serum thyroid stimulating hormone. Successful treatment was defined as euthyroid and hypothyroid.
Results: A total of 179 patients (126 females; mean age: 40.8 years) were enrolled. One patient was excluded from the outcome analysis due to undetermined laboratory results. The success rate of RAI therapy was 50% (95% CI: 42.4-57.6). Patients with gland size ≤ 50 gm had the highest success rate of 59.6%. Multivariable analysis showed no significant association between sex, thyroid gland size, and prior antithyroid drug use and successful treatment.
Conclusion: First RAI therapy using dose corrected for thyroid gland size had a modest success rate of 50% in patients with Grave’s disease. Sex, thyroid gland size, and prior antithyroid drug use were not significantly associated with the treatment outcome.


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Kiatkittikul, P., Raruenrom, Y., Theerakulpisut, D., & Somboonporn, C. (2021). Success Rate of Radioactive Iodine Therapy in Graves’ Disease Using Dose Corrected for Thyroid Gland Size : . Siriraj Medical Journal, 73(2), 108–113.
Original Article


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