From thyroid therapy to systemic crisis: PTU-induced c-ANCA vasculitis accompanied by cold-agglutinin disease and organ failure

Introduction: Propylthiouracil (PTU) is typically used as first line therapy for hyperthyroidism but is associated with a spectrum of adverse effects including vasculitis, that may lead to acute renal failure and exceptionally to pancreatitis, represents the most severe. Case description: Here we present the case of a 43-year-old woman with a history of Graves' disease until recently on PTU therapy, who presented with fever and myalgia complicated by cold agglutinin disease, acute renal failure and pancreatitis. Subsequent laboratory studies and thorough physical examination excluding other causes revealed the presence of antibodies against leukocyte proteinase 3. Prompt initiation of immunosuppressive therapy and plasmapheresis led to immediate improvement of the patient's clinical condition and laboratory tests. Conclusion: Clinicians should maintain a high index of suspicion for autoimmune phenomena in patients receiving PTU even after cessation of the medication. Early recognition, immediate discontinuation of the drug, and timely initiation of immunosuppressive therapy are essential to prevent irreversible organ damage. LEARNING POINTS: Propylthiouracil is a well described trigger for the development of drug-induced vasculitis, seldom even long after cessation of therapy.In patients presenting with multi-organ failure the differential diagnosis should broaden to include systemic autoimmune vasculitis with atypical features.The cornerstone of therapy in drug induced autoimmune vasculitis is the immediate withdrawal of the offending agent and initiation of immunosuppressive therapy.