Thyroid stimulating antibodies, thyroglobulin antibodies and serum proteins during treatment of Graves' disease with radioiodine or propylthiouracil.

The relation between serum concentrations of thyroglobulin antibodies (TgAb), thyroid-stimulating antibodies (TSAb) and serum immunoglobulins during treatment of Graves' disease was studied in 36 consecutive patients treated randomly with 131-iodine (n = 16) or propylthiouracil (n = 20). The patients were investigated before treatment was started and on seven occasions within the following year. In the entire patient group 78% were positive for TSAb and 47% for TgAb. There was a significant correlation between TSAb and TgAb in 15 patients concomitantly positive. There were no significant changes in serum immunoglobulins during treatment in either group of patients. In the radioiodine-treated group of patients TgAb was reduced after 1 week, whereas TSAb showed insignificant variations. After 5-10 weeks both antibodies increased, for TgAb with a median peak level 3 time above the initial concentration. Of 16 patients treated with radioiodine five developed myxoedema and four of these were positive for TgAb. There was a relation between the development of myxoedema and the ratio between increases of TSAb and TgAb. Increase in TSAb was not related to serum thyroglobulin (Tg) measured in TgAb-negative patients. Propylthiouracil showed minor effects on the studied variables, but with lower mean values of Tg, TgAb and TSAb at the end of the observation period. The results indicate an immunological relation between TSAb and TgAb, although differences between their course exist in some situations.