ABSTRACT
Objective To investigate the incidence of radioactivity uptake in thymus combined with serum thyroglobulin (Tg) increase in differentiated thyroid cancer (DTC) patients after high-dose 131I treatments,in order to discuss the mechanism of thymus iodine uptaking and Tg increasing.Methods Retrospective analysis of the laboratory examinations and 131Iwhole body scan (131I-WBS) images in 316 DTC patients were performed.The radioactivity uptake in thymus and the Tg level were observed.Results Among 316 patients (total 735 case-times),4 patients of 5 cases-times 131I-WBS showed radioactivity uptake in thymus,accounting for 0.68％ (5/735).All the radioactivity uptake in thymus were found by posttreatment 131I whole body scan (Rx-WBS) and after the second radioactive iodine treatment.For 1 of 4 patients,Rx-WBS still showed thymic uptake 131I after the third radioactive iodine treatment.The serum Tg increased in 3 patients (4 caestimes Rx-WBS) of radioactivity uptake in thymus with the Tg level before Rx-WBS was 13.80 μg/L,＞300.00 μg/L,16.40 μg/L,20.60μg/L,respectively.Conclusion In order to avoid the inappropriate administration of radioiodine therapy,thymic uptake should be identified carefully in DTC patients whose radioactivity uptake is only found at the upper mediastinal and combined with serum Tg increase.