Snapshot A 21-year-old woman with past medical history of SLE presents with fever, fatigue, and altered mental status. On physical exam, a petechial rash is seen on her upper extremities. Her temperature is 103°F (39.4°C). Her labs are notable for Hgb 7.3 g/dL, platelets 17,000/mm3, and creatinine of 3.4 mg/dL. Introduction Thrombotic microangiopathy characterized by a pentad microangiopathic hemolytic anemia acute renal failure thrombocytopenia fever neurologic abnormalities Similar to HUS but with fever and neurologic symptoms Epidemiology female > male most commonly in young adults Pathogenesis deficiency or inhibition of metalloproteinase ADAMTS13 most commonly disabled by an autoantibody ADAMTS13 degrades vWF multimers deficiency → large vWF multimers → increased platelet adhesion → platelet thrombosis important underlying risk factor, but requires a secondary trigger triggers drugs (ticlopidine, clopidogrel, and cyclosporine) SLE Presentation Symptoms (recall pentad) thrombocytopenia easy bleeding epistaxis neurological symptoms confusion seizures thrombosis renal dysfunction (less so than HUS) Physical exam fever pallor (from anemia) purpura/petechiae jaundice (from hemolysis) splenomegaly Evaluation Complete blood count anemia thrombocytopenia Peripheral blood smear schistocytes (helmet cells) Serum ↑ LDH ↑ creatinine negative Coomb’s ↑ bleeding time normal PT/PTT Differential Diagnosis DIC HUS Sepsis Treatment Plasma exchange transfusion with fresh frozen plasma Steroids Splenectomy Platelet transfusion contraindicated platelet transfusion will worsen disease by feeding the platelet consumption Prognosis, Prevention, and Complications Prognosis remission with plasma exchange in majority of patients mortality rate 13-15% Complications permanent neurologic sequelae