A Case of Thrombotic Thrombocytopenic PurpuraInitially Suspected as Shiga Toxin-Producing Escherichia coli Hemolytic Uremic Syndrome Due to the Preceding Symptoms of Hemolytic Anemia with Vomiting, Hematochezia, and AKI

Introduction: Thrombotic Thrombocytopenic Purpura (TTP) should be suspected in patients presenting with microangiopathic hemolytic anemia and severe thrombocytopenia. Additional findings indicative of TTP include significantly elevated lactate dehydrogenase, elevated indirect bilirubin and negative Coombs testing. Creatinine levels may be normal or slightly elevated, with levels exceeding 2 mg/dL being uncommon. Here, we report a case of TTP with features resembling hemolytic uremic syndrome (HUS), including vomiting, hematochezia, and acute kidney injury. Case Description: A 59-year-old man developed vomiting, hematochezia, and gross hematuria after eating sashimi. After receiving intravenous therapy at a local clinic without improvement, the patient was transferred to our hospital. At admission, the patient's temperature was 37.2°C. Urinalysis showed proteinuria 2+, and hematuria 3+. The blood test revealed hemoglobin 7.3 g/dL, reticulocytes 4.1%, schistocytes 3‰, platelet count 5,000/μL, serum creatinine 2.41 mg/dL, C-reactive protein 0.89 mg/dL, lactate dehydrogenase 1,160 U/L, indirect bilirubin 2.6 mg/dL, and haptoglobin 2 mg/dL.Based on the clinical symptoms and laboratory findings, HUS caused by Shiga toxin-producing Escherichia coli (STEC) was suspected. The patient received continuous fluid therapy but developed oliguria, leading to initiation of hemodialysis on the second day. On the third day, seizures and confusion occurred. We diagnosed TTP and initiated steroid pulse therapy and plasma exchange. On the fifth day, ADAMTS13 activity was confirmed to have dropped to 1%, along with the detection of an ADAMTS13 inhibitor. The stool culture was negative. Thrombocytopenia, consciousness disorders, and renal dysfunction gradually improved. Dialysis ended successfully on the 7th day. Subsequently, rituximab was given, and the patient was discharged on the 38th day with no recurrence. Discussion: The classic pentad of TTP symptoms comprises thrombocytopenia, microangiopathic hemolytic anemia, neurological issues, kidney dysfunction, and fever. However, these symptoms and lab findings may not occur simultaneously. It is crucial to maintain a high level of suspicion for TTP during management, even when atypical symptoms or laboratory values are present.