B12 Deficiency: An Overlooked Case of Microangiopathic Hemolytic Anemia

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Case Presentation: A 32-year-old female with a history of untreated sarcoidosis and gastric bypass surgery with partially treated B12 deficiency in the past, was admitted for shortness of breath with a primary diagnosis of pancytopenia. Patient had not taken B12 injections for close to 2 years. Her labs were consistent with severe pancytopenia (Hemoglobin 5.4, White blood cell count 1.8, Platelets 78000) with lab evidence of massive hemolysis on peripheral smear (schistocytes) and chemistries (severely increased Lactate dehydrogenase 2377, reticulocytes 2.5% and decreased haptoglobin <30). B12 levels (<50) and folate levels (5.4) were severely depressed. Coombs test was negative on two separate occasions. Patient responded to packed red blood cell transfusion, however she continued to show signs of ongoing hemolysis. Hematology was consulted who started patient for possible immune mediated hemolytic anemia with intravenous immunoglobulin and prednisone. We determined that microangiopathic hemolytic anemia can be explained by B12 deficiency alone, given patient’s pancytopenia prior response to B12 injections. Treatment was simplified with discontinuation of intravenous immunoglobulins and initiations of supplementation with B12 injections and oral folate. Patient complete blood count after a month of treatment with B12 injections showed immense improvement in hemoglobin to 12.5 and WBC to 4.1.

Discussion: Massive hemolytic anemia is a rare and potentially lethal complication of B12 deficiency. B12 is usually attributed to megaloblastic anemic with severe forms of deficiency causing pancytopenia’s. However, severe B12 deficiency is an under-documented etiology for treatable microangiopathic hemolytic anemia. Severe hemolysis with low reticulocyte counts, schistocytes on peripheral smear and very high Lactate dehydrogenase should raise the suspicion of severe B12 deficiency.

Conclusions: B12 supplements in patients with severely depressed B12 levels with hemolysis is a simple fix for an apparently life-threatening condition and avoids the need for unnecessary interventions.


Abstract number 1061. Presented at Hospital Medicine 2019, March 26, 2019, National Harbor, MD

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