Identification of Optimal Fixed Radioactive Iodine Dose for Radioactive Iodine Treatment in the Patients with Benign Thyroid Disease Associated with Hyperthyroidism: Retrospective study

Abstract

Aim: In this study, we aimed to examine the effectiveness of our approach to determining of the ambulatory low iodine-131 (I-131) dose performed in our clinic for the hyperthyroidism by retrospectively analyzing data of patients that received a low dose of I-131 in our institution for the treatment of hyperthyroidism. Material and Methods: Medical records of 140 patients that received a ambulatory low dose of I-131 treatment in our institution were retrospectively reviewed. A total of 103 patients with available complete follow-up data were included: 15 patients with Graves’ disease (GD), 36 patients with toxic adenoma (TA), and 52 patients with toxic multinodular goiter (TMNG). Age, sex, concomitant conditions other than thyroid disease, type and treatment duration of antithyroid medications, I-131 dose administered, and the presence and duration of response to RIT were recorded for each patient. Development of hypothyroidism or euthyroidism following RIT was considered as treatment response for patients with GD, whereas development of euthyroidism was an indication of treatment response for patients with toxic nodular goiter. Results: Of 103 patients, 71 were female and 32 were male (mean age: 60 ± 12 years). The mean I-131 doses administered to patients with GD and toxic nodular goiter were 333 ± 74 MBq and 666 ± 148 MBq, respectively. Based on our treatment response criteria, our cure rates for GD, TA, and TMNG were 73.3%, 55.6%, and 65.4%, respectively. The mean duration of follow-up was 9 ± 6 months. Ninety patients received single dose and 13 patients received two doses of I-131. Hypothyroidism developed in 10 patients with GD and TA, and in 13 patients with TMNG. The mean time to hypothyroidism following a single dose was 3 ± 1 months for patients with GD and TA, and 4 ± 1 months for TMNG patients. Cumulative cure rates following the second doses were as follows: 93.3% for GD, 63.9% for TA, and 71.2% for TMNG. Conclusion: The ambulatory I-131 doses used in our institution for the ambulatory treatment of benign thyroid diseases associated with hyperthyroidism were found to be effective.

Key words: Hyperthyroidism, Radioactive iodine, Therapy

Special Issue of Health Sciences

DOI: 10.7176/JSTR/6-03-17