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

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.