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The prevalence and clinical significance of blocking thyrotropin receptor antibodies in untreated hyperthyroid

W B Kim1, H K Chung, Y J Park

  • 1Department of Internal Medicine, Seoul National University College of Medicine and Center for Hormone Research, Seoul National University Hospital, Korea.

Thyroid : Official Journal of the American Thyroid Association
|August 25, 2000
PubMed

Insights

Blocking thyrotropin receptor antibodies (TSHRAb) are present in nearly 20% of Graves' disease patients. These blocking TSHRAb may lead to underestimation of stimulating TSHRAb activity and are associated with a higher prevalence of exophthalmos.

Area of Science:

  • Endocrinology
  • Immunology
  • Ophthalmology

Background:

  • Graves' disease is an autoimmune disorder characterized by hyperthyroidism.
  • Thyrotropin receptor antibodies (TSHRAb) play a key role in the pathogenesis of Graves' disease.
  • TSHRAb can be either stimulating or blocking, influencing disease activity and clinical presentation.

Purpose of the Study:

  • To evaluate the clinical significance of blocking TSHRAb in patients with hyperthyroid Graves' disease.
  • To determine the prevalence of blocking TSHRAb in this patient population.
  • To investigate the association between blocking TSHRAb and clinical features, including ophthalmopathy.

Main Methods:

  • Measurement of stimulating and blocking TSHRAb in 200 untreated hyperthyroid Graves' disease patients.
  • Utilized various cell lines, including Chinese hamster ovary (CHO) cells with wild-type human TSHR and chimeric receptors (Mc2, Mc1+2), and FRTL-5 cells.
  • Clinical features, such as age, gender, T4 levels, goiter size, and exophthalmos, were compared between patients positive and negative for blocking TSHRAb.

Main Results:

  • Blocking TSHRAb were detected in 18.5% of patients.
  • Patients with blocking TSHRAb showed significantly lower mean stimulating TSHRAb activities in wild-type CHO-hTSHR cells compared to those without blocking antibodies (p = 0.005).
  • A higher prevalence of exophthalmos was observed in patients with blocking TSHRAb (35.1%) compared to those without (17.5%, p = 0.024).

Conclusions:

  • The presence of blocking TSHRAb is relatively common in hyperthyroid Graves' disease when assessed using chimeric receptor cells.
  • Blocking TSHRAb may underestimate stimulating TSHRAb activity measured by CHO-hTSHR cells.
  • The association of blocking TSHRAb with ophthalmopathy suggests distinct TSHRAb profiles in Graves' patients with and without eye disease.

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