Pernicious anaemia

Question 1

What does vitamin B12 deficiency cause?

Answer 1

Macrocytic anaemia

Question 2

What are the key causes of low B12?

Answer 2

Pernicious anaemia, Insufficient dietary B12, Medications which reduce B12 absorption

Question 3

What is pernicious anaemia?

Answer 3

An autoimmune condition involving antibodies against parietal cells or intrinsic factor

Question 4

What is the pathophysiology of pernicious anaemia?

Answer 4

Parietal cells of stomach produce a protein called intrinsic factor which is essential for absorption of vitamin B12 in distal ileum. In pernicious anaemia, autoantibodies target the parietal cells or intrinsic factor hence lack of absorption of vit B12.

Question 5

What neurological symptoms can vitamin B12 deficiency cause?

Answer 5

Peripheral neuropathy, with numbness or paraesthesia, Loss of vibration sense, Loss of proprioception, Visual changes, Mood & cognitive changes

Question 6

What antibodies are associated with pernicious anaemia?

Answer 6

Intrinsic factor antibodies, Gastric parietal cell antibodies

Question 7

What is the initial management for vitamin B12 deficiency?

Answer 7

IM hydroxycobalamin, 3x weekly for 2 weeks, if no neurological symptoms. If neurological symptoms - alternate days.

Question 8

What is the maintenance management for vitamin B12 deficiency?

Answer 8

Depends on cause. Pernicious anaemia - 2-3 monthly injections for life. Diet related - oral cyanocobalamin or twice yearly injections.

Question 9

What do you do if a patient has both B12 and folate deficiency?

Answer 9

Treat B12 deficiency first before correcting folate deficiency. If you give patients folic acid when they have B12 deficiency it can lead to subacute combined degeneration of the cord, with demyelination of the spinal cord - severe neurological problems.