Life-threatening megaloblastic pancytopenia with normal mean cell volume: Case series

The mean red blood cell volume (MCV) is usually increased in severe megaloblastic anemia due to pernicious anemia. However, during one year in a university hospital, three patients with life-threatening pancytopenia and normal MCV were proven to have severe vitamin B12 deficiency. The red blood cell distribution width was markedly increased (three times normal) and led to review of the blood smear and recognition of megaloblastosis as well as prominent red cell fragmentation. These three cases illustrate that vitamin B12 status should be evaluated in cases of pancytopenia, independent of the MCV value.