Table 1.

Elements of the hematological manifestations of vitamin B12 deficiency

CBC: genuine aregenerative, normochromic, and macrocytic anemia; generally associated with moderate leukopenia and thrombopenia.

Blood smear: large red blood cells, anisocytosis, Howell–Jolly bodies, and globular-shape cells in the form of ovalocytes; large-size granulocytes with hypersegmentation of the nuclei (shift to the right in Arneth’s formula).

Biology: elevated serum levels of LDH and free bilirubin and decreased levels of haptoglobin (hemolysis by ineffective intramedullary erythropoiesis).

Spinal smear: rich and bluish spinal fluid due to cytoplasmic hyperbasophilia; increased medullary erythroblastosis with megaloblastic erythroblasts. All stages of erythroid maturation are represented but the asynchrony of nucleocytoplasmic maturation is marked by immature nuclei and an already acidophilic cytoplasm.

Abbreviations: CBC, complete blood count; LDH, lactate dehydrogenase.