Vitamin B12 deficiency Cobalamin

• Facts:
  Vitamin B12 is a necessary cofactor in the pathway leading to purine synthesis
  
  Deficiency leads to decreased DNA synthesis and erythropoesis, leading to megaloblastic anemia
• History / PE:
  Macrocytic anemia (MCV > 100)
  Peripheral neuropathy
  Glossitis
• Diagnosis:
  Increased homocysteine and methylmalonic acid (MMA)
  Schilling test (helps differentiate between PA and malabsorption)
• See Also:
  Vitamin B deficiency
• Associated With:
  Pernicious anemia (PA)
  Diphyllobothrium latum (tapeworm)
  Celiac disease
  Vegatarianism (after 3-4 years)
  Partial / total gastrectomy
• Differential Diagnosis:
  Folic acid deficiency (only increased homocysteine , no neurological signs)