Drug-induced immune thrombocytopenia (DITP) refers to drug-dependent, antibody-mediated platelet destruction. Although several drugs have been implicated as the cause of DITP, the most commonly encountered are heparin, sulfonamides, quinine, vancomycin, and beta-lactam antibiotics. However, furosemide has been rarely reported as the cause of thrombocytopenia. We present a unique case of furosemide-induced thrombotic thrombocytopenia in a 64-year-old female referred by her primary care provider for low platelets, rash, and bleeding. She was recently started on oral furosemide for diastolic heart failure two weeks before this presentation. She was admitted to the intensive care unit and was worked up for new-onset thrombocytopenia. Labs revealed anemia, thrombocytopenia, elevated lactate dehydrogenase, and low haptoglobin with normal serum creatinine. Peripheral smear showed schistocytes, low platelets, and ADAMTS13 level was 0.03. The patient was diagnosed with thrombotic thrombocytopenic purpura and treated with steroids, rituximab, and plasmapheresis, which led to rapid recovery of the platelet count to normal. Based on this case report, clinicians should consider furosemide as one of the drugs potentially causing thrombotic thrombocytopenia. Early detection and prompt management can be lifesaving.

Thrombotic thrombocytopenic purpura (TTP) is a thrombotic microangiopathy (TMA) caused by severely reduced ADAMTS13 or the von Willebrand factor-cleaving protease (VWFCP) enzyme resulting in low platelet and red blood cell counts along with severe renal, cardiac, and neurological dysfunction. Plasmapheresis is the treatment of choice. Mitomycin, a widely used chemotherapeutic agent for gastrointestinal (GI) cancers anal and breast cancers, has been reported to occasionally cause severe TTP and hemolytic uremic syndrome (HUS) cases. Here, we present a case of a 57-year-old African American transgender patient who presented with worsening kidney function, thrombocytopenia, and anemia following mitomycin therapy for her anal squamous cell carcinoma. Peripheral smear showed numerous schistocytes, and the patient was diagnosed with TTP because of low ADAMTS13 levels. The patient was started on plasmapheresis and steroid with ultimate improvement in condition. TTP is a rare condition that can be idiopathic or acquired. Further research is required to assess the complexity of the underlying mechanism. Early diagnosis and aggressive management often lead to a favorable outcome.