Clinical Features of Patients with Basedow's Disease and High Serum IgG4 Levels

Objective IgG4-related disease is a recently characterized condition presenting with high blood IgG4 levels, swelling of organs, and hypertrophic lesions. This disease is associated with thyroid disease, Hashimoto's disease, and Riedel's thyroiditis. However, there is little information on the association between IgG4-related disease and Basedow's disease. We herein defined the clinical features of patients with Basedow's disease and high IgG4 levels. Methods We compared two groups of patients with Basedow's disease (n=72) who had either normal IgG4 levels (<135 mg/dL; n=67) or high IgG4 levels (≥135 mg/dL; n=5 [6.9%], mean IgG4: 206±116 mg/dL, IgG4/IgG ratio: 10.6%±3.3%). Patients Seventy-two newly diagnosed, untreated patients with Basedow's disease. Results Compared to the normal IgG4 group, patients in the high IgG4 group were predominantly male and showed a significantly higher thyroid low-echo score (1.8±0.4 vs. 1.2±0.5) and eosinophil count (363±354/mm² vs. 136±122/mm²). Five patients had high IgG4 levels: one had a pancreatic lesion, and four had thyroid lesions. Conclusion Patients with Basedow's disease and high IgG4 levels may represent a new subtype of Basedow's disease. Further studies with larger sample sizes are needed.