Vitamin B12 Deficiency

Question 1

What is B12 used for in the body?

Answer 1

Red cell development & maintenance of the nervous system.

Question 2

Where and how is it absorbed into the body?

Answer 2

It binds to intrinsic factor (secreted from parietal cells in the stomach) and is actively absorbed in the terminal ileum.

Question 3

What are some causes of vitamin B12 deficiency?

Answer 3

• Pernicious anaemia
• Post gastrectomy
• Poor diet
• Disorders of terminal ileum (site of absorption): Crohn’s, blind-loop etc
• Metformin (rare)

Question 4

What are some clinical features of B12 deficiency?

Answer 4

• Macrocytic anaemia
• Sore tongue and mouth
• Neurological symptoms: e.g. Ataxia
• Neuropsychiatric symptoms: e.g. Mood disturbances

Question 5

How do you manage B12 deficiency?

Answer 5

• If no neurological involvement 1 mg of IM hydroxocobalamin:
  
  • 3 times each week for 2 weeks
  • Then once every 3 months
• If folic acid deficiency, treat the B12 deficiency first
  
  • To avoid precipitating subacute combined degeneration of the cord.