TSH-receptor autoimmunity in Graves' disease after therapy with anti-thyroid drugs, surgery, or radioiodine: a 5-year prospective randomized study.

INTRODUCTION Autoimmunity against the TSH receptor is a key pathogenic element in Graves' disease. The autoimmune aberration may be modified by therapy of the hyperthyroidism. OBJECTIVE To compare the effects of the common types of therapy for Graves' hyperthyroidism on TSH-receptor autoimmunity. METHODS Patients with newly diagnosed Graves' hyperthyroidism aged 20-55 years were randomized to medical therapy, thyroid surgery, or radioiodine therapy (radioiodine was only given to patients > or = 35 years of age). L-thyroxine (L-T4) was added to therapy as appropriate to keep patients euthyroid. Anti-thyroid drugs were withdrawn after 18 months of therapy. TSH-receptor antibodies (TRAb) in serum were measured before and for 5 years after the initiation of therapy. RESULTS Medical therapy (n=48) and surgery (n=47) were followed by a gradual decrease in TRAb in serum, with the disappearance of TRAb in 70-80% of the patients after 18 months. Radioiodine therapy (n=36) led to a 1-year long worsening of autoimmunity against the TSH receptor, and the number of patients entering remission of TSH-receptor autoimmunity with the disappearance of TRAb from serum during the following years was considerably lower than with the other types of therapy. CONCLUSION The majority of patients with Graves' disease gradually enter remission of TSH-receptor autoimmunity during medical or after surgical therapy, with no difference between the types of therapy. Remission of TSH-receptor autoimmunity after radioiodine therapy is less common.