Changes of serum TRAb after 131I radiotherapy in patients of Graves hyperthyroidism

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. 1 5 ) U/L)]was noted in patients before 131J 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. Key words: Graves disease;  Iodine radioisotopes;  Receptors, thyrotropin;  Antibodies;  Devlopmental changes