MON-409 A Case of Recurrent Graves' Disease Associated with IgG4-releated Disease

Abstract Disclosure: F.N. Connor-Recio: None. J. Colón Castellano: None. Immunoglobulin-G4-related thyroid disease (IgG4-RTD) is a medically treatable disease and quick diagnosis is imperative as rapid progression of the disease can result in unnecessary surgery. IgG4-RTD is a condition that associates thyroid diseases with a spectrum of IgG4-related disease (IgG4-RD). Four subcategories of IgG4-RTD have so far been identified: Riedel thyroiditis (RT), fibrosing variant of Hashimoto thyroiditis (FVHT), IgG4-related Hashimoto thyroiditis, and Graves’ disease with elevated IgG4 levels. The pathogenesis of IgG4-RTD involves genetic factors, antigen-antibody reactions, and allergic phenomena, but remains poorly understood. Due to insufficient awareness of this clinical entity, the prevalence of IgG4-RTD is likely to be underestimated. This is a 47-year-old male with history of recurrent Graves’ disease that has reached remission twice with methimazole, Hepatitis C infection s/p 8 weeks of ledipasvir/sofosbuvir, chronic uncomplicated pancreatitis of unknown etiology. The patient presented to endocrine clinics as follow up referring pressure-like chest pain associated with palpitations mostly at rest of 1-2 min duration that self-resolved and started around one month ago. While physically active, felt more agitated but denied chest pain. Also reported dry and itchy eyes that had been worsening and unintentional weight loss. The patient described these symptoms like when he was first diagnosed with Graves’ disease. Vital signs were essentially normal except for tachycardia. Physical exam remarkable for goiter without tenderness to palpation, bilateral gynecomastia, adequate hair distribution, no peripheral edema, deep tendon reflexes with normal relaxation phase, no exophthalmos nor conjunctival injection or stare. Pertinent laboratories included elevated IgG4 of 154.3 mg/dL (normal 4-86 mg/dL), suppressed TSH of <0.005 uIU/mL (normal 0.460-4.980 uIU/mL) and elevated TSI at 416% (normal <=140%). Patient was subsequently oriented about definitive treatment alternatives such as thyroidectomy and radioblation but opted for medical therapy. In addition, he was oriented about the use of Rituximab together with methimazole to increase the probability of remission in context of IgG4-RTD, however he refused.This case further illustrates an association between IgG4-RTD with Graves’ disease. The pathogenesis is still unclear, and precise diagnostic criteria are not yet defined. Studies have shown a higher prevalence of thyroid eye disease in these patients. Physicians should consider the possibility of IgG4-RTD in a patient with recurrent Graves’ disease as recognizing it promptly can be crucial in evaluation and management for other IgG4-RTD. Furthermore, recognition of this association might lead to development of new therapeutic approaches for example use of Rituximab in combination with anti-thyroid drugs to induce remission. Presentation: Monday, July 14, 2025