Dupilumab-Induced Graves' Disease in an Adult With Chronic Rhinosinusitis and Nasal Polyposis.

Dupilumab, a monoclonal antibody targeting interleukin-4 (IL-4) and IL-13, is widely used for the treatment of type 2 inflammatory conditions such as atopic dermatitis, asthma, and chronic rhinosinusitis with nasal polyposis. Although generally well-tolerated, dupilumab has been linked to rare thyroid-related events. We report a case of Graves' disease (GD) in a 47-year-old man with severe nasal polyposis who developed heat intolerance and weight loss within six to eight weeks of starting dupilumab. Laboratory tests confirmed thyrotoxicosis with positive thyroid-stimulating hormone receptor antibodies (TSHR-Ab), leading to a GD diagnosis. The patient was started on methimazole and remains stable on both methimazole and dupilumab. The temporal association between dupilumab initiation and the detection of TSHR-Ab suggests a possible link between dupilumab therapy and the development of GD. This may be mediated by a shift from Type 2 helper T cells (Th2) to Type 1 helper T cells (Th1) immune dominance, which is known to promote autoimmune thyroid activity. Such a mechanism is biologically plausible and consistent with current immunopathogenic models of GD. This case adds to the limited literature on dupilumab-associated autoimmune thyroid disease. Physicians should consider monitoring thyroid function in patients on dupilumab, especially those with immune-mediated conditions. Further studies are needed to clarify this mechanism and guide screening guidelines.