Vitamin B12 Deficiency
At a Glance Diagnosis of vitamin B12 (cobalamin) deficiency is relatively straightforward in long-lasting deficiency, which manifests itself with marked anemia, macrocytosis (mean corpuscular volume [MCV] > 100 fL with ovalocytosis, possibly in conjunction with thrombocytopenia and neutropenia > pancytopenia) neutrophil hypersegmentation (at least 5% of neutrophils with 5 lobes or at least 1% with…