Vitamin B12

Vitamin B2, also called cobalamin, is a water-soluble vitamin that has a key role in the normal functioning of the brain and nervous system via the synthesis of myelin (myelinogenesis), and the formation of red blood cells.

Vitamin B12 deficiency is most commonly caused by low intakes, but can also result from malabsorption, certain intestinal disorders, low presence of binding proteins, and use of certain medications. Vitamin B12 is rare in plant sources, so vegetarians are more likely to suffer from vitamin B12 deficiency. Infants are at a higher risk of vitamin B12 deficiency if they were born to vegetarian mothers. The elderly who have diets with limited meat or animal products are vulnerable populations as well. Vitamin B12 deficiency may occur in between 40% to 80% of the vegetarian population.

Indications / Clinical use:

• Diagnosis of vitamin B12 deficiency
• Clinical features: macrocytic anemia, glossitis, peripheral neuropathy, cognitive impairment.
• Laboratory findings: megaloblastic anemia, elevated MCV, possible pancytopenia.

Investigation of macrocytosis or megaloblastic anemia
Differentiates vitamin B12 deficiency from folate deficiency.

Evaluation of neurological or psychiatric symptoms
Cognitive decline, peripheral neuropathy, myelopathy, depression—especially in the elderly.

Monitoring in at-risk populations

• Dietary deficiency: vegans, malnutrition.
• Malabsorption syndromes: pernicious anemia, celiac disease, Crohn’s disease, gastric surgery.
• Drug-related causes: prolonged metformin, proton pump inhibitors, H2 antagonists.
  
  

Therapeutic monitoring
Assess response to supplementation in patients with confirmed deficiency.