This report describes the case of a woman with severe vitamin B12 deficiency from pernicious anemia. Her clinical presentation, which involved microangiopathic hemolytic anemia (MAHA), was presumed to be thrombotic thrombocytopenic purpura (TTP). TTP is a rare life-threatening condition with high mortality and morbidity rates. It is caused by a severe deficiency of ADAMTS13, an enzyme which cleaves the von Willebrand factor in the clotting cascade. This case report highlights the importance of early recognition of TTP and other causes of MAHA. We explore the pathogenesis and management of severe, life-threatening vitamin B12 deficiency.

Case Presentation

A 51-year-old woman presented to the hospital with progressive shortness of breath and anasarca. Initial workup revealed severe hemolytic anemia, thrombocytopenia, and schistocytes on blood smear, concerning for thrombotic thrombocytopenic purpura (TTP). She received rapid treatment with plasmapheresis and prednisone with only mild response. Further workup revealed the diagnosis of severe vitamin B12 deficiency caused by pernicious anemia.


Vitamin B12 has been previously associated with TTP-like presentation. However, the exact pathogenic mechanism for such a presentation is not fully understood. One proposed mechanism suggests hyperhomocysteinemia as a causative factor for hemolysis.


Causes of MAHA, besides TTP, including severe vitamin B12 deficiency should be considered as part of differential workup, although it should not delay the initiation of plasma exchange for suspected cases of TTP.