Case Presentation: A 44-year-old African American female patient was admitted with fatigue and anorexia from an outpatient clinic visit after she was found to be profoundly anemic with hemoglobin of 6.8 g/dL. She endorsed a history of chronic anemia of unknown etiology, was prescribed oral iron on several occasions but did not take it due to pill induced dysphagia. She denied any history of chronic blood loss, or specific diet preferences or any history suggestive of a malabsorptive state. Family history was significant for an anemia of unknown origin in her mother and maternal grandmother, both requiring periodic transfusions. Physical exam was positive for conjunctival pallor. There was no evidence of hepatosplenomegaly, lymphadenopathy or skin rash. Cardiopulmonary, abdominal and neurologic exam were unremarkable. Initial evaluation revealed pancytopenia with WBC count of 3.07 x 10^3/uL and platelet count of 71000/cu.mm. Further evaluation for anemia revealed a low serum haptoglobin <20, a high LDH-3072 U and a corrected reticulocyte count-1.2%.The MCV was 91 and RDW was 29.2 %, consistent with a hemolytic anemia like picture except for the reticulocyte count which was inappropriately low. A peripheral blood smear was reviewed with a hematopathologist revealing a normocytic normochromic anemia with minimal schistocytes and a significant number of tear drop cells and hypersegmented neutrophils. The peripheral blood smear picture was classic for megaloblastic anemia. Serum B12 and folate levels were drawn and found to be <63 pg/mL and 19.7 ng/mL, respectively. This finding was consistent with profound vitamin B12 deficiency which can lead to pancytopenia, anisopoikilocytosis resulting in high RDW, elevation in hemolytic markers secondary to hemolysis in the bone marrow and low reticulocyte count due to ineffective erythropoiesis. Serum methylmalonic acid was markedly elevated at 18,694 nmol/L, further supporting the diagnosis of B12 deficiency. Work up for the etiology of Vitamin B12 deficiency revealed very high titers of anti-intrinsic factor antibodies which led to the diagnosis of pernicious anemia. Her family history of chronic anemia was also supporting the diagnosis. The patient was treated with intramuscular B 12 injections once daily for seven days, followed by weekly for four weeks and subsequently monthly for life. After the first few doses, her blood counts were improving. Within 4 weeks of treatment, her WBC and platelet count were normal and hemoglobin improved to 11 gm/dl.
This was a classic presentation of Vitamin B12 deficiency secondary to pernicious anemia. Vitamin B12 deficiency results in megaloblastic anemia which presents as macrocytic anemia mostly. It is important to recognize that it can also result in pancytopenia and hemolysis like picture resulting from the bone marrow lysis of early RBC precursors due to lack of substrate (vitamin B12) for nuclear and cytoplasmic maturation. This is a very treatable condition provided a complete work up is done and Vitamin b12 is replaced appropriately. It is important to determine the etiology as this would help decide on the route of administration of Vitamin B12.
Understanding the underlying process of bone marrow hemolysis and ineffective erythropoiesis and myelopoiesis in Vitamin B12 deficiency is important in making a unifying diagnosis. This case provides a great understanding of the pathophysiology of megaloblastic anemia which is beyond just a macrocytic anemia.
To cite this abstract:Mani S, Mehdi A, Hussain U. Classic Presentation of an Unusual Cause of Anemia. Abstract published at Hospital Medicine 2016, March 6-9, San Diego, Calif. Abstract 678. Journal of Hospital Medicine. 2016; 11 (suppl 1). https://www.shmabstracts.com/abstract/classic-presentation-of-an-unusual-cause-of-anemia/. Accessed April 5, 2020.