Correlation between thyroid 24 h of radioactive iodine uptake and clinical efficacy of 131I therapy for Graves′ hyperthyroidism

Abstract

Objective To evaluate the correlation between 24 h of radioactive iodine uptake (24 h RAIU) and clinical efficacy of 131I therapy for Graves′ hyperthyroidism. Methods Data of 3218 patients with Graves′ hyperthyroidism from August 2009 to July 2014 were collected after a follow-up study. The follow-up times were 6 months to 60 months (mean: 28.36±14.06 months) . All patients underwent radioactive 131I therapy for the first time in the first hospital of Shanxi medical university. A total of 2690 patients (83.6% of 3218 patients) were followed up. These patients comprised 855 males and 1835 females, with ages ranging from 11 years to 81 years (average: 42.81 ± 15.06 years) . Patients were treated with 131I therapy doses of 74 MBq to 1850 MBq (mean dose: 402.50±279.94 MBq) and divided into three groups based on thyroid 24 h RAIU before 131I therapy as follows: group A, 405 cases (24 h RAIU 80.0%) . Additionally, the patients were divided into two groups based on the follow-up results of patients treated with 131I therapy. The cured group consisted of cases that were healed or had presented hypothyroidism, whereas the uncured group comprised cases with improved, invalid, and recurrent conditions. Results A total of 2690 patients with Graves′ hyperthyroidism were treated with radioactive131I, of which 2244 cases were cured (83.4%) , and 446 cases were uncured (16.6%) . In group A, 360 cases (88.9%) were cured, and 45 cases (11.1%) were uncured. In group B, 1534 cases (87.0%) were cured, and 230 cases (13.0%) were uncured. In group C, 350 cases (67.2%) were cured, and 171 cases (32.8%) were uncured. Statistically significant differences were found between the cured and uncured rates among the three groups (χ2=21.80, P<0.05) . Multivariate linear regression results indicated that age (b=0.259) , thyroid weight (b=0.340) , gender (b=0.275) , and use of anti-thyroid drugs (ATD) treatment (b=0.226) were all correlated with thyroid 24 h RAIU. Conclusion Thyroid 24 h RAIU was related to the clinical efficacy of 131I therapy for Graves′ hyperthyroidism. Low 24 h RAIU implies high cure rate, whereas high 24 h RAIU indicates high failure rate. High 24 h RAIU was primarily caused by high thyroid weight, young age, female gender, and lack of ATD treatment. By contrast, low thyroid weight, old age, male gender, and history of ATD treatment can lead to low 24 h RAIU. Overall, this study will provide further information regarding clinical 131I treatment of Graves′ hyperthyroidism. Key words: Graves disease; Iodine radioisotopes; Hyperthyroidism; Treatment outcome