MON-412 Immune Thrombocytopenic Purpura Induced by Propylthiouracil: A Clinical Exploration

Abstract Disclosure: A. Patel: None. D. Wenkert: None. Background: Graves' disease, a common autoimmune thyroid disorder, is frequently associated with hyperthyroidism and related complications. Immune thrombocytopenic purpura (ITP) is a rare but serious autoimmune condition characterized by isolated thrombocytopenia, leading to an increased risk of bleeding. Furthermore, Graves' disease itself carries a risk of developing immune thrombocytopenic purpura (ITP), and this risk can be further exacerbated by the use of Propylthiouracil (PTU) as a treatment, as seen in this case. Case Presentation: A 55-year-old female with a 1-year history of diagnosed Graves' disease presented with sudden onset of daily epistaxis, and petechiae to the clinic after being started on PTU a month prior to the clinic visit. She also reported dyspnea on exertion, palpitations and weight loss prior to being placed on PTU. Laboratory tests performed during the clinic visit revealed a low platelet count (2,000/µL), FT4 of 1.41 ng/dl and TSH of 0.003 uIU/mL. The patient was referred to the ER for management of thrombocytopenia and was later admitted to the hospital for further workup. Given the timing of the patient’s clinical symptoms and laboratory findings, ITP due to the initiation of PTU was strongly suggested. Management and Outcome: The patient was treated for ITP with Decadron 4mg daily for four days and discontinuation of PTU during the hospital admission. Regular monitoring of platelet counts, and thyroid function was implemented. The patient showed a positive response to corticosteroid therapy, with a significant improvement in platelet count and a reduction in bleeding symptoms. Patient’s platelets increased to 34,000 during the hospital stay and platelets increased to 123,000, five days after discharge. The patient was taken off methimazole in the past due to transaminitis. Continued follow-up is planned to monitor for potential relapse of ITP and the long-term management of Graves’ disease, specifically thyroidectomy by Endocrine Surgery in this case. Conclusion: This case highlights the rare but significant association between Graves' disease treatment and ITP, emphasizing the importance of a broad approach to treatment. A few studies have suggested that the incidence of PTU causing ITP is between 1 in 1,100 to 1 in 10,000. Managing both autoimmune conditions requires careful balancing of immunosuppressive therapies while addressing the risk of thyroid complications. Early recognition and coordinated care are critical to optimizing outcomes for patients with coexisting autoimmune disorders. Presentation: Monday, July 14, 2025