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

• Arora S
• Bal C

• KMID: 2512964
• DOI: http://doi.org/10.1007/s13139-020-00674-3

Abstract

Purpose
To compare ¹³¹I-therapy outcomes in high turnover and normal turnover Graves’ disease patients and predict optimal first ¹³¹I activity for high turnover patients.
Methods
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.
Results
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.
Conclusion
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.

Keyword

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