IgG4 as a Biomarker in Graves' Orbitopathy

Area of Science:

• Endocrinology
• Immunology
• Rheumatology

Background:

• Immunoglobulin G4-related disease (IgG4-RD) is a systemic fibroinflammatory condition.
• Recent research links IgG4 to autoimmune thyroid diseases, establishing IgG4-related thyroid disease.
• This study focuses on IgG4's role in Graves' disease (GD) and Graves' orbitopathy (GO).

Purpose of the Study:

• To describe the pathophysiological, histopathological, and clinical features of Graves' Disease (GD) and Graves' Orbitopathy (GO) in patients with elevated IgG4 levels.
• To differentiate GD and GO with elevated IgG4 from those with normal IgG4 levels.

Main Methods:

• Literature review and analysis of existing studies on IgG4 levels in GD and GO patients.
• Comparison of clinical, ultrasound, and laboratory findings between groups with elevated and normal IgG4 levels.

Main Results:

• Elevated serum IgG4 levels are found in 10.3% of GD patients and 17.6% of GO patients.
• GD with elevated IgG4 shows lower thyroid echogenicity, eosinophilia, higher GO prevalence, and better response to antithyroid drugs.
• GO with elevated IgG4 presents at a younger age and has a more severe course (higher CAS).

Conclusions:

• Elevated IgG4 levels in GD and GO patients signify distinct clinical characteristics and potential treatment implications.
• Diagnosis of GO with elevated IgG4 should be considered in GD patients with ophthalmic symptoms and high IgG4.
• Further research is warranted to elucidate the precise role of IgG4 in thyroid autoimmunity and orbitopathy.