Case Presentation: A 68 year old female patient presented to the emergency department after being found down at her house. On exam she was found to be confused and disoriented. Lab work showed severe pancytopenia, and elevated bilirubin with no associated elevation of LFTs. She was transfused with 2 units of packed red blood cells and 1 unit of platelets. She was found to have dried blood around her mouth and nose and endorsed a history of alcohol use, but denied a history of cirrhosis. She was started on IV ceftriaxone, octreotide, and pantoprazole. Endoscopy was done showing no signs of inflammation or bleeding. Further workup showed elevated LDH, low haptoglobin, normal reticulocyte count, and low levels of B12 with associated elevations of homocysteine and methylmalonic acid. Peripheral smear confirmed the presence of multi-segmented neutrophils. She was started on a 7 day course of IM B12 injections to correct the deficiency. She was subsequently found to have Intrinsic Factor antibodies, confirming a diagnosis of Pernicious Anemia.
Discussion: This case demonstrates the importance of having a broad differential when approaching a case of pancytopenia. In the setting of severe anemia with a history of alcohol use, it is easy to assume that bleeding is the likely cause. However, a workup showing hemolysis should prompt the astute physician to explore other causes that better explain the clinical picture. Pernicious anemia is a common cause of B12 deficiency, which can infrequently lead to severe pancytopenia due to intramedullary hemolysis and megaloblastic changes to myeloid precursor cells.
Conclusions: B12 deficiency in a patient generally presents itself innocuously as a macrocytic anemia, and has even been known to occasionally present with neuropsychiatric derangements. However, there are some potentially catastrophic consequences if B12 deficiency becomes severe enough. In rare circumstances, B12 deficiency can actually result in pancytopenia and hemolytic anemia, and should be considered in the differential when a patient presents with signs of a hemolytic anemia.