B73-50 Unusual Expectoration of Fibrinous Bronchial Cast-Like Material Following Initiation of Semaglutide in a Patient With Obesity

Abstract Rationale Semaglutide, a GLP-1 receptor agonist, is widely used for weight reduction and glycemic control. While gastrointestinal adverse effects are well recognized, pulmonary complications have not been reported. Expectoration of bronchial cast-like fibrinous material, consistent with plastic bronchitis, is rare and typically associated with infection, congenital heart disease, or lymphatic disorders. We describe an unusual case temporally associated with semaglutide initiation. Methods A 34-year-old patient with class III obesity, prediabetes, hypertension, and generalized anxiety disorder presented for evaluation of spontaneous passage of green, tubular, bronchial cast-like material. Current medications included alogliptin/pioglitazone, telmisartan/hydrochlorothiazide, atorvastatin, sertraline, vitamin D, etoricoxib, and semaglutide initiated four weeks prior. The patient denied fever, dyspnea, chest pain, hemoptysis, or persistent cough. Chest radiography demonstrated no infiltrates or consolidation. Histopathologic examination of the expelled fragments showed fibrin with plant fibers and autolytic changes, without microorganisms. No eosinophilia, elevated inflammatory markers, or infectious triggers were identified. Symptoms resolved spontaneously after semaglutide discontinuation, with no recurrence. Results The temporal association with semaglutide initiation, negative infectious and imaging studies, absence of recurrent pulmonary symptoms, and clinical resolution after drug withdrawal suggest a medication-related adverse effect. Possible mechanisms include GLP-1-mediated gastrointestinal dysmotility leading to micro-aspiration. Conclusion We report a case of fibrinous bronchial cast expectoration potentially associated with semaglutide use. Clinicians should be aware of possible airway manifestations in patients receiving GLP-1 receptor agonist therapy, particularly when atypical sputum production or unexplained respiratory symptoms occur. This case raises the hypothesis that GLP-1 therapy may contribute to the development of plastic bronchitis through its known effects on delayed gastric emptying, increased risk of gastroesophageal reflux, and episodes of nausea or vomiting. This abstract is funded by: none