RESUMO
To investigate the possible participation of immunoglobulin E (IgE) in the autoimmune process of Graves' disease, incidence of elevation of serum IgE level, TSH receptor antibody (TRAb), and thyroid status were studied in 66 patients with hyperthyroid Graves' disease, 54 patients with Hashimoto's thyroiditis, 19 patients with bronchial asthma, and 15 patients with pollen allergy. In hyperthyroid Graves' patients, elevation of serum IgE levels (> or = 170 U/mL) was found in 19 of 66 patients (29%), 11 of whom had hereditary and/or allergic conditions. Elevations of serum IgE levels were found in 63% of patients with bronchial asthma and in 40% of patients with pollen allergy. Mean values of serum IgE were the same in patients with hyperthyroid Graves' disease and with bronchial asthma. During methimazole treatment TRAb decreased without fluctuation of IgE levels in both groups. The decrease in TRAb was significantly greater in patients with normal IgE than in patients with IgE elevation. After prednisone administration, reduction in TRAb was greater in patients with normal IgE than that in patients with IgE elevation. High incidence of IgE elevation in hyperthyroid Graves' disease and slower reduction in TRAb in association with IgE elevation suggest a difference in the autoimmune processes in Graves' disease with and without elevation of IgE.
