Vitamin B12 Deficiency

Macrocytic Anemia.  MCV >100 fL
  • MCV usually very high (>110)
  • May not have frank anemia
Draw serum B12 level
  • If low, order Intrinsic Factor Antibody (IFA) to Dx Pernicious Anemia (PA)
If B12 low-normal, can still be Pernicious Anemia.
  • Order Methylmalonic Acid (MMA) & Homocysteine (HC)
  • If MMA & HC are high, order IFA
IFA only 90% sensitive for PA
  • If low B12, or high MMA & HC, Dx PA even if IFA neg
  • PA is common in elderly
  • Gold standard Shilling Test no longer available
PA is bad:
  • Neuro sequelae (neuropathy, dementia) may be worse than anemia
  • Neuro Sx can occur without anemia
  • Tx: Vit. B12 shots 1 mg (1,000 mgm) IM, given daily x1 wk, then weekly x1 mo., then monthly forever
  • Can also Tx oral B12, 1-2 mg per day forever, if adherence adequate

See posting Anemia – 3.

Advertisements