Abstract
A radioreceptor assay of TSH using Triton-solubilized human thyroid receptors was applied to the detection of TSH-binding inhibitor immunoglobulins (TBII). In 26 untreated patients with Graves'disease, 20 (76.9%) were found positive in this assay, while 18 (69.2%) cases were found positive by the conventional assay using human thyroid particulate receptors. In 25 patients with goitrous Hashimoto's thyroiditis, 2 (8.0%) were found positive by the assay using soluble receptor, while 3 (12.0%) were found positive by the conventional one. A significant correlation was found between TBII activities in the patients with untreated Graves' disease detected by these two assay systems (r=0.69; n=26; p<0.001). These data support the concept that TBII are antibodies against the TSH receptor or its closely related structures.
