The presence of higher levels of thyroglobulin, but not thyroid autoantibodies, in the thyroid vein in Graves’ disease

To investigate the possible major source of thyroid autoantibodies production, blood samples were obtained from thyroid vein, jugular vein and peripheral vein during subtotal thyroidectomy in 12 patients with Graves’ disease (11F, 1M; age 16–39 yr). Among them, 7 were treated preoperatively by methimazole, 4 by iopanoic acid and 1 by propranolol. All blood samples were assayed for thyroglobulin (Tg), thyrotropin binding inhibition immunoglobulin (TBII), antithyroglobulin antibody (TgAb) and antimicrosomal antibody (McAb). Tg, a native product of thyroid gland, was markedly elevated in the thyroid veins, over 4 to 6 folds that of jugular veins or peripheral veins. However, the level of thyroid autoantibodies including TBII, TgAb and McAb in the thyroid veins were not significantly different from that in the jugular or peripheral veins. Our preliminary data suggest that it is thyroglobulin, and not thyroid antibodies that is present at higher level in the thyroid vein than the periphery.