B12 (Cyanocobalamin) - as methyl-cobalamin; adenosyl-cobalamin

needed by 2 enzymes:

Homocysteine methyltransferase

Methylmalonyl-CoA mutase, SAM

used to make tetrahydrofolate

used to recycle Odd-numbered carbon fatty acids;

Val, Met, Ile, Thr

VOMIT pathway

Deficiency -

Mcc: pernicious anemia (type A gastritis)/ lack of intrinsic factor, destruction of gastric parietal cells/gastrectomy, celiac sprue, entritis, diphyllobothrium latum (fish or broad tapeworm), chron's disease, surgery, etc.

Strong risk factors for Vit B12 Deficiency

• Age >65
• Gastric bypass surgery or Gastric Resection
• Terminal ileum disease (Crohn's disease )
• Metformin use
• Strict Vegetarian

Feautres:

• Megaloblastic anemia
• hypersegmented neutrophils