Serial changes and clinical significance of TGAb and TMAb before and after radioiodine treatment for Graves' disease

Objective: To study the changes and their clinical effect of levels of thyroglobulin (TGAb) and thyroid microsomal autoantibody (TMAb) in sera during radioiodine treatment of Graves' disease. To investigate early therapeutic effect of radioiodine and influence factors for early hypothyroidism. Methods: 328 patients were divided into positive group (TGAb > 30%, TMAb > 20%) and negative group (TGAb<30%, TMAb<20%) according to TGAb and TMAb levels before 131I treatment. The levels of TT3, TT4, FT3, FT4, TSH, TGAb and TMAb in serum were measured before 131I therapy and at the 3rd, 6th, 9th, 12th months after treatment respectively. Results: Within one year after radioiodine treatment, 22.8% patients (53 out of 232) in the positive group and 8.3% (8 out of 96) in the negative group suffered from early hypothyroidism, and significant difference existed in the two groups. After radioiodine treatment, the positive rate of TGAb and TMAb was gradually reduced with time. Conclusion: The probability of early hypothyroidism is related to the level of TGAb and TMAb before treatment. Measurement of TGAb and TMAb could help to design radioiodine dose. And treatment of Graves' disease with 131I could reduce the level of thyroid autoantibodies and promote the improvement and recovery of autoimmunity status