The medical mystery in the October 30 issue1 concerned a 71-year-old man with a 10-day history of dizziness, progressive lethargy, and confusion. A complete blood count showed pancytopenia (white-cell count, 2900 per cubic millimeter [normal range, 4000 to 11,000]; hemoglobin, 5.5 g per deciliter [normal range, 14 to 18]; hematocrit, 14.5% [normal range, 40 to 52]; and platelets, 56,000 per cubic millimeter [normal range, 150,000 to 440,000]) as well as macrocytosis (mean cell volume, 118 µm3 [normal range, 82 to 98], with a red-cell distribution width of 22,300 per cubic millimeter [normal range, 10,500 to 15,500]) and a reticulocyte count of 0.4% (normal range, 1.2 to 3.2). The patient reported occasional alcohol use, and there was no evidence of a toxic ingestion or nutritional deficiencies. He had no known autoimmune disease or endocrinopathies. Additional laboratory work showed a vitamin B12 deficiency (B12, 75 pg per milliliter [normal range, 240 to 900]; folate, 6.2 ng per milliliter [normal range, 2.0 to 20]). His peripheral-blood smear showed macroovalocytes (Figure 1A, arrowheads) and hypersegmented neutrophils (Figure 1A, arrow). A bone marrow aspirate, performed to evaluate pancytopenia, showed megaloblastic erythroid precursors (Figure 1B, arrowheads) and giant bands (Figure 1B, arrow). The patient was treated with folic acid, 5 mg daily by mouth for 2 months, and vitamin B12 replacement. A complete blood count obtained 7 months later showed a normalization of the red-cell count indexes. Pernicious anemia is suspected but has not been confirmed.
NEJM Volume 359:2845-2846 December 25, 2008 Number 26
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