A case of Graves' disease and papillary thyroid carcinoma with predominant production of thyroid-stimulation-blocking antibodies (TSBAb) persisted after total thyroidectomy.

A 42-year-old female with Graves' disease and papillary thyroid carcinoma with lung metastasis was referred to our hospital. After treatment of thyrotoxicosis with methimazole and Lugol's solution, she underwent total thyroidectomy. She was then given 131I twice to treat lung metastasis. However, 131I uptake into the lung was not clear in the scintigram. Both thyroid-stimulating antibodies (TSAb) and thyroid-stimulation-blocking antibodies (TSBAb) were detected in her sera before and after the treatments. Compared with TSAb activities, TSBAb activities were extremely high. Changes in the titers of these two antibodies were not clear after total thyroidectomy. These results indicate that lymphocytes outside the thyroid gland are the major source of TSAb and TSBAb in this patient.