Pernicious Anemia Presenting With Pseudo Thrombotic Microangiopathy and Falsely Elevated B 12 Levels

Pseudo thrombotic microangiopathy is a distinct clinical entity that is seen in patients with B12 deficiency. We describe a patient who presented with microangiopathic hemolytic anemia, thrombocytopenia, altered mentation and renal insufficiency. Thrombotic thrombocytopenic purpura was a major concern; however the peripheral blood smear showed hypersegmented neutrophils and the altered mental status as well as renal dysfunction improved with red cell transfusions. It was concluded that her clinical picture was more consistent with ineffective erythropoiesis, which can mimic thrombotic thrombocytopenic purpura (TTP). She was ultimately diagnosed with pernicious anemia based on positive intrinsic factor antibody, elevated methylmalonic acid, and homocysteine levels. Her B12 levels were falsely elevated which confounded the diagnosis. Distinguishing between these two conditions is imperative to avoid unwarranted plasmapheresis.