Objective: To assess the affection of serum TRAb on short-term prognosis of early-onset hypothyroidism after the patients with hyperthyroidism received radioiodine therapy.Methods: There were 62 patients with hyperthyroidism who became early-onset hypothyroidism within 3 months after 131I treatment in the study.23 male, 39 female, mean age 37.4±11.7 (range 14~60 years old).The total time of follow-up were 12~42 months.The parameters of the patients including FT3, FT4, sTSH and TRAb were collected before and at 3,6,12 months after radioiodine treatment.The results of last time follow-up after 131I treatment were regard as the final thyroid hormone level of the patients.The results were statistically analyzed using repeated measures analysis of variance.Results: Sixty-two patients with hyperthyroidism who became early-onset hypothyroidism after 131I therapy were followed up.The outcome of follow-up showed there were 31 patients with hypothyroidism [including group1∶ 22 cases with rise TRAb (26.2±45.4, 114.5±97.0, 42.9±53.2 and 16.8±23.3) and group3∶9 cases with continuing normal TRAb (2.8±2.8, 4.8±3.2, 3.9±2.6 and 2.6±3.1) at different time intervals], 27 patients with normal thyroid hormones level (group2)(TRAb: 33.8±56.8, 153.8±113.1, 145.6±74.3 and 80.9±58.9), 4 cases of recurrence (group4) (TRAb: 19.9±15.0, 163.9±96.1, 130.1 ±108.1 and 66.0±44.8).There were significant differences among TRAb values before and at different time intervals after radioiodine therapy in 4 groups (F1 in groups=1 4.78, P<0.001, F2 at different time intervals=19.67, P<0.001).Conclusions: 1.The gradual descent of rise TRAb values signified that the patients with early-onset hypothyroidism who were from hyperthyroidism after radioiodine treatment would be likely to be euthyroid.2.The continuing normal of TRAb values at different time intervals showed that the patients with early-onset hypothyroidism who were from hyperthyroidism after radioiodine treatment would be likely to be late-onset hypothyroidism.