A NEW SIMPLE, PERSONALIZED, AND QUANTITATIVE EMPIRICAL METHOD FOR DETERMINING 131I ACTIVITY IN TREATING GRAVES' DISEASE.

Abstract

The 131I activity for treating Graves' disease (GD) is usually determined based on physician's experience. This study aimed to design an empirical method that was not only personalized and quantitative, but also simple, convenient, and easy to grasp. The study population comprised patients with GD, selected between May 2013 and May 2016, who received 131I therapy in the Outpatient Department of Shanghai Ninth People's Hospital. The first-visit patients of physician 1 were placed in the traditional group: the activity of 131I (mCi) was calculated using the routine formula: [empirical activity (0.07-0.12 mCi/g) × thyroid mass]/[24-h thyroid 131I uptake]. The first-visit patients of physician 2 were placed in the personalized group. The activity of 131I (mCi) was calculated in two steps. First, the initial activity was calculated: 0.1 mCi/g × thyroid mass (g), and then a personalized and quantitative calibration table of 131I activity was used to obtain a final 131I activity. The cure rate with a single activity of 131I was recorded 1 year later. The traditional and personalized groups included 241 and 282 patients, respectively. Interestingly, the personalized group achieved a higher cure rate [86.5% (244/282) versus 73.4% (177/241), P = 0.000] with a relatively higher 131I activity for the first treatment [8.7 (7, 3.5-30) mCi versus 6.7(6, 2.5-30) mCi, P = 0.000] compared with the traditional group, while the incidence rate of permanent hypothyroidism was not significantly different between the two groups (P = 0.175). The empirical method designed in this study was reliable.