A Rare Case of Severe Pernicious Anemia with Neuropsychiatric Implications

BACKGROUND Pernicious anemia (PA) is caused by a deficiency in intrinsic factor (IF), which is necessary for vitamin B12 (cobalamin) absorption, resulting in vitamin B12 deficiency and subsequent megaloblastic anemia. Diagnosis of PA relies on the detection of circulating antibodies to IF. In addition to anemia, patients can develop neuropsychiatric conditions, such as subacute combined degeneration of the spinal cord or psychosis. We present the case of a patient with a history of schizophrenia who exhibited unusually severe manifestations of pernicious anemia, including life-threatening anemia, multiple hypersegmented neutrophils, and significantly elevated methylmalonic acid (MMA) levels. CASE REPORT A 51-year-old Hispanic woman with a history of schizophrenia was admitted with severe weakness, shortness of breath, and diarrhea. The hemoglobin (Hb) level was 2.5 g/dL and mean corpuscular volume (MCV) was 133 fL. A diagnosis of pernicious anemia was made by a low vitamin B12 level, high levels of methylmalonic acid (MMA) and homocysteine, and positive IF-blocking antibodies. Her anemia did not improve initially, even after 3 units of blood were transfused. She had no signs of bleeding. It was thought that hemoconcentration due to severe dehydration falsely raised her initial Hb levels, which were corrected by hydration. A peripheral blood smear showed many hypersegmented neutrophils. With parenteral cyanocobalamin therapy, her anemia and schizophrenia symptoms improved. The hypersegmented neutrophils disappeared by 2 weeks. CONCLUSIONS This is an extreme case of pernicious anemia with life-threatening anemia. The hypersegmented neutrophils disappeared in 2 weeks with vitamin B12 therapy. The symptoms of schizophrenia also improved.