[Serum superoxide dismutase in patients with Graves' disease]

We studied serum superoxide dismutase (SOD) in patients with Graves' disease. Measurements of immunoreactive Cu, Zn-SOD and SOD-like activities were made by enzyme-linked immunosorbent assay (Ube Industries Ltd) and Nitroblue Tetrazolium method (Wako Ltd), respectively. Serum from patients with untreated Graves' disease had a significantly higher concentration of Cu, Zn-SOD and higher SOD-like activity than those from normal subjects, patients with Graves' disease under treatment over one year, patients with Graves' disease in remission, and patients with untreated Hashimoto's disease. Methimazole treatment produced no significant change in SOD-like activity and Cu, Zn-SOD concentration when patients with Graves' disease had normal thyroid function. These results indicated that oxidative tissue injury existed in patients with Graves' disease with normal thyroid function under treatment; however, we could not clearly establish that thyroid function had a direct connection with oxidative tissue injury.