Nucl Med Mol Imaging.  2021 Feb;55(1):15-26. 10.1007/s13139-020-00674-3.

Is There Any Need for Adjusting 131 I Activity for the Treatment of High Turnover Graves’ Disease Compared to Normal Turnover Patients? Results from a Retrospective Cohort Study Validated by Propensity Score Analysis

  • 1Department of Nuclear Medicine, All India Institute of Medical Sciences, New Delhi 110029, India


To compare 131I-therapy outcomes in high turnover and normal turnover Graves’ disease patients and predict optimal first 131I activity for high turnover patients.
Retrospective cohort design (1:2) validated by propensity score analysis. Cohort 1, high turnover (2-h RAIU/24-h RAIU ≥ 1), n = 104, and cohort 2, normal turnover (ratio < 1), n = 208, patients were compared for post 131I outcome. The cure was defined as a combined euthyroid and stable hypothyroid state following 131I treatment. Logistic regression analysis was used for identifying prognostic factors. The propensity score was applied; 77 matched pairs (1:1 ratio) of high and normal turnover patients were selected as a validation set.
First 131I cure rates of 28% in high turnover and 66% in normal turnover groups (p = 0.001) were noted. The therapy cycles (median, 2 vs. 1) and cumulative 131I activity (median, 15 vs. 7 mCi) were required to cure hyperthyroidism in cohort 1 and cohort 2, respectively. Age (> 44 years), higher grade of goitre, and 2-h RAIU (> 37%) were associated with 131I therapy failure. The high turnover patients needed a factor of 1.5–2 times more 131I activity to achieve a similar cure rate compared to the normal turnover patients. The first-dose cure rate was 31% vs. 60% by propensity score analysis (n = 154), no way different (28% vs.66%) from the whole group of 312 patients.
High turnover Graves’ disease patients, if administered standard 131I activity, the outcomes shall be poor. To improve the success rate, 131I activity should be increased by 1.5 to 2 times in the high turnover patients.


Graves’ disease; Turnover; High turnover; Normal turnover; Radioiodine therapy
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