The bioassay of
thyroid-stimulating immunoglobulin was reported to have a similar performance to the commonly used
thyroid-stimulating hormone binding inhibition assay, also known as thyroid receptor antibody assay. The normal reference range of thyroid receptor antibody levels indicates the withdrawal of anti-thyroid drugs in the recent clinical guidelines.
METHODS: A total of 77 patients with
Graves' disease treated with anti-thyroid drugs were in a continuous follow-up until 1 year after anti-thyroid drugs discontinuation. Commercial kits of
thyroid-stimulating immunoglobulin and M22-thyroid-stimulating
hormone binding inhibition assay were used and compared.
Thyroid-stimulating immunoglobulin was all negative in healthy controls,
Hashimoto thyroiditis, and
subacute thyroiditis.
Thyroid-stimulating immunoglobulin value was highest in untreated patients with
Graves' disease (p < 0.001). Under anti-thyroid drugs treatment,
thyroid-stimulating immunoglobulin value decreased gradually. A total of 21 patients had positive
thyroid-stimulating immunoglobulin at the end of treatment. According to clinical fate of patients with
Graves' disease after withdrawal of anti-thyroid drugs,
thyroid-stimulating immunoglobulin value and positivity in patients with relapse were significantly higher than that reported in patients with remission (p = 0.001, p < 0.001). After adjustment for age, gender, initial thyroid receptor antibody, initial
thyroid-stimulating immunoglobulin, and thyroid receptor antibody at the end of treatment, the odds ratio of positive
thyroid-stimulating immunoglobulin for the risk of relapse was 33.271 (95% confidence interval: 4.741-233.458, p < 0.001) and odds ratio of quantitative
thyroid-stimulating immunoglobulin was 1.009 (95% confidence interval: 1.002-1.015, p < 0.001).
CONCLUSION: