Vitamin B12 Deficiency in Thrombotic Thrombocytopenic Purpura-Like Cases.

ABSTRACT

Background: Thrombotic microangiopathies (TMA) are characterized by a triad of microangiopathic hemolytic anemia, thrombocytopenia, and organ damage which occur in the setting of endothelial damage and platelet activation. Vitamin B12 (cobalamin) deficiency could lead to a picture that resembles TMA, termed metabolic mediated TMA (MM-TMA). Case Presentation A 60-year-old female was brought to the hospital after she was found unresponsive. On presentation, she was pale, lethargic, tachycardic, and febrile. Laboratory investigations revealed normocytic anemia, thrombocytopenia, and elevated bilirubin. Blood smear revealed schistocytes and tear drop cells. Given the presence of hemolytic anemia, thrombocytopenia, acute renal failure, and altered mental status, a presumptive diagnosis of thrombotic thrombocytopenic purpura (TTP) was made with a PLASMIC score of 7 indicating high risk. She received plasma exchange, caplacizumab, and intravenous methylprednisolone. Given the patient's low level of vitamin B12, she was initiated on intramuscular cyanocobalamin 1000 µg daily. The encephalopathy resolved and renal function improved. On day 6, ADAMTS13 activity was normal ruling out the diagnosis of TTP. Accordingly, plasmapheresis, steroids, and caplacizumab were discontinued. With continued aggressive B12 replacement, hemolysis resolved indicating severe vitamin B12 deficiency was the likely culprit of this patient's microangiopathic hemolytic anemia. Conclusion: This case serves to highlight the variable presentation of vitamin B12 deficiency. Severe vitamin B12 deficiency can even mimic TTP. If patients have markers of hemolysis, a low vitamin B12 level, and low reticulocyte count we should consider vitamin B12 deficiency as a likely cause of microangiopathic hemolytic anemia as early detection allows for early initiation of appropriate management. LEARNING POINTS Vitamin B12 deficiency can be a cause of thrombotic microangiopathy.