Changes in serum thyroglobulin and thyroid autoantibodies in patients with Graves' disease treated with antithyroid drug and their relationship to relapse.

Abstract

Serum thyroglobulin (Tg) levels are elevated in some patients with Graves' disease. Several studies have pointed out the usefulness of this fact in predicting the outcome of the disease. Among the various antibodies, the antithyroglobulin (ATA) and antimicrosomal (AMA) antibodies are valuable in screening for thyroid autoimmunity. The aim of this study was to analyze the changes in serum Tg and autoantibodies during the course of antithyroid drug therapy and to evaluate their prognostic value. Serum Tg was measured by double antibody RIA, and ATA and AMA by the semiquantitative tanned red cell hemagglutination method in 65 patients before and after antithyroid therapy. Forty-two patients (64.6%) experienced a relapse and 23 patients (35.4%) remained in remission at the end of the study. The changes in the ATA or AMA titers, measured prior to and following therapy were nonsignificant in both groups. While the titers of ATA and AMA before and after therapy were not different between the two groups, there was a tendency for the patients with a positive ATA after therapy to have a relapse. When ATA-positive cases were excluded, there was no change in the Tg levels in either group. The Tg levels of the relapse group either before or after therapy were significantly higher than those of the remission group. There was no difference in T3 or T4 before therapy between the two groups. There was no relationship between the Tg levels after therapy and the duration of remission in either group. In conclusion, during the course of antithyroid therapy, patients with a relapse of Graves' disease had higher serum Tg levels, either before or after therapy.(ABSTRACT TRUNCATED AT 250 WORDS)