Serum Thyrotropin Receptor Antibodies Concentrations in Patients with Graves' Disease Before, at the End of Methimazole Treatment, and After Drug Withdrawal: Evidence That the Activity of Thyrotropin Receptor Antibody and/or Thyroid Response Modify During the Observation Period

TRAb persist in the blood of most patients with GD after 18 months of MMI treatment. Both the frequency and the time of appearance of hyperthyroidism are closely correlated with serum TRAb concentrations at the end of MMI treatment. Our data would suggest that TRAb maintain stimulating activity after a full course of MMI treatment in the large majority of patients with GD. However, it is likely that the potency of these antibodies and/or the thyroid response to them change during treatment, as suggested by the different values measured in euthyroid control subjects and in euthyroid patients after MMI treatment.