VITAMIN B12 (VB12)
1 SST/1.0 mL serum (0.5 mL minimum). After 30 minutes of clotting, promptly centrifuge and refrigerate,
Refrigerated: 48 hours; Frozen: 2 months
Vitamin B12 and folate are critical to normal DNA synthesis, which in turn affects erythrocyte maturation. VB12 is also necessary for myelin sheath formation and maintenance. Clinical and laboratory findings for VB12 deficiency include neurological abnormalities, decreased serum VB12 levels, and increased excretion of methylmalonic acid. The impaired DNA Synthesis associated with VB12 deficiency causes macrocytic anemias. These anemias are characterized by abnormal maturation of erythrocyte precursors in the bone marrow, which results in the presence of megaloblasts and in decreased erythrocyte survival. Pernicious anemia is a macrocytic anemia caused by VB12 deficiency that is due to lack of intrinsic factor. Low VB12 intake, gastrectomy, diseases of the small intestine, malabsorption, and trans-cobalamin deficiency can also cause VB12 deficiency.