B12 defiency

Question 1

Role of B12 in the body?

Answer 1

mainly used in the body for red blood cell development and also maintenance of the nervous system.

Question 2

How is B12 absorbed?

Answer 2

absorbed after binding to intrinsic factor (secreted from parietal cells in the stomach) and is actively absorbed in the terminal ileum. A small amount of vitamin B12 is passively absorbed without being bound to intrinsic factor.

Question 3

Causes of vitamin B12 deficiency

Answer 3

pernicious anaemia: most common cause

post gastrectomy

vegan diet or a poor diet

disorders/surgery of terminal ileum (site of absorption)
- Crohn’s: either diease activity or following ileocaecal resection

metformin (rare)

Question 4

Features of vitamin B12 deficiency

Answer 4

macrocytic anaemia

sore tongue and mouth

Neurological symptoms
- the dorsal column is usually affected first (joint position, vibration) prior to distal paraesthesia

• Neurophsyciatric symptoms eg. mood disturbances

Question 5

Features of vitamin B12 deficiency

Answer 5

macrocytic anaemia

sore tongue and mouth

Neurological symptoms
- the dorsal column is usually affected first (joint position, vibration) prior to distal paraesthesia

• Neurophsyciatric symptoms eg. mood disturbances

Question 6

Management: B12 deficiency

Answer 6

if no neurological involvement 1 mg of IM hydroxocobalamin 3 times each week for 2 weeks, then once every 3 months

if a patient is also deficient in folic acid then it is important to treat the B12 deficiency first to avoid precipitating subacute combined degeneration of the cord