Objective To study the changes of serum thyrotrophin receptor antibody(TRAb) in patients of Graves' hyperthyroidism after ¹³¹I radiotherapy and explore its clinical significances.

Methods A total of 128 patients and 45 nomal controls were included in the study. Serum concentration of TRAb was measured by radioreceptor assay before and at 3, 6, 12 and 18 months after ¹³¹I radiotherapy.

Results The TRAb level of 45 nomal controls was (2.95±1.48) U/L. Abnormally higher TRAb level(81.52±36.15)U/L)was noted in patients before ¹³¹I treatment(t=8.17, P < 0.01). The TRAb titer increased further to(127.13±49.05)U/L at 3 months after therapy(t=4.92, P < 0.01), before it dropped to (59.82±28.51)U/L and (12.53±9.26)U/L at 6 and 12 months respectively(t=6.89 and t=2.29, P < 0.01). At 18 months after ¹³¹I radiotherapy, the level of TRAb (4.29±2.56)U/L)was back to normal with no difference to that of controls(t=1.53, P > 0.05).

Conclusion It is of great significance to measure serum concentrations of TRAb after ¹³¹I radiotherapy, which is of important clinical value for therapy guidance, efficacy assessment, recurrence prediction and hypothyroidism identification.