(6.12) A Case of PTU-Induced Vasculitis

Thionamides are used for the management of hyperthyroidism. Side effects range from mild to severe. Severe adverse effects include agranulocytosis, hepatotoxicity, and rarely, vasculitis. In this case report, we describe a case of propylthiouracil (PTU)-induced vasculitis.

Case(s) Description :

A 41-year-old man with Graves’ disease presented with a 2-week history of skin ulcers that have been increasing in size and number, along with subjective fevers. Graves’ disease was diagnosed in 2019 and his Endocrinologist initiated him on Methimazole. Unfortunately, he failed to follow up until 2022, when he presented to his PCP who initiated him on PTU management. His labs on admission revealed pancytopenia and elevated inflammatory markers. Autoimmune work up revealed positive antinuclear (ANA), myeloperoxidase (MPO), and proteinase-3 (PR3) antibodies. Additionally, biopsy of a skin lesion performed earlier in his admission resulted positive for leukocytoclastic vasculitis. His hospital course was complicated by worsening shortness of breath and development of diffuse alveolar hemorrhage. He was therefore treated with intravenous steroids for three days followed by oral steroids and hydroxychloroquine. After two weeks of hospitalization, he was clinically stabilized and discharged home on prednisone, hydroxychloroquine, and trimethoprim-sulfamethoxazole.

Discussion :

Antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis is a necrotizing form of vasculitis, predominately affecting small vessels. It is characterized by the presence of autoantibodies against cytoplasmic constituents of neutrophils and monocytes, designated as ANCAs. ANCAs in the vasculitides can be directed against proteinase 3 (PR3) or myeloperoxidase (MPO). Renal involvement is the most common manifestation in thionamide-induced vasculitis, followed by skin and lung involvement. Most patients with thionamide-induced vasculitis have positive antibodies against MPO or PR3, along with other autoantibodies, including ANA, anti-histone, or anti-cardiolipin antibodies. About one-third of patients have positive antibodies against both PR3 and MPO. In addition to MPO-ANCA and PR3-ANCA, our patient’s labs also demonstrated positivity for ANA, anti-SSA, and anti-SSB. Given the heterogeneity of presentation, patients should be educated to alert their physician of symptoms such as fever, rash, hematuria, or hemoptysis. If symptoms are suggestive of vasculitis, the suspected offending agent should be immediately discontinued. Additionally, the patient’s labs should be evaluated with a complete blood count, a comprehensive metabolic panel, c-reactive protein, erythrocyte sedimentation rate, and ANCA levels. Symptoms are expected to improve soon after discontinuation of the offending agent. We recommend the decision to begin treatment with corticosteroids and/or immunosuppressive agents to be made in conjunction with a consulting Rheumatologist. In our patient, prompt detection of hematologic abnormalities allowed for a rapid cessation of PTU administration and consultation with sub-specialties, leading to an excellent recovery.