Haematology - pernicious anaemia

Question 1

What is pernicious anaemia?

Answer 1

An autoimmune cause of vitamin B12 deficiency

Antibodies against intrinsic factor or against parietal cells. Intrinsic factor is essential for absorption of vitamin B12

Lack of Intrinsic factor prevents absorption of vitamin B12 and therefore deficiency

Question 2

Symptoms of vitamin B12 deficiency

Answer 2

Anaemia symptoms

Peripheral neuropathy (numbness or paraesthesia)

Loss of vibration sense or proprioception

Visual changes

Mood or cognitive changes

Question 3

Diagnosing pernicious anaemia

Answer 3

Testing for auto-antibodies is used to diagnose pernicious anaemia.

Intrinsic factor antibody is the first line investigation

Gastric parietal cell antibody can also be tested but is less helpful

Question 4

Management of pernicious anaemia

Answer 4

Cannot give oral vitamin B12 replacement due to absorption problem

So treat with 1g IM hydroxocobalamin (3 times weekly for 2 weeks and then every 3 months)

Question 5

Treating dietary deficiency of vitamin B12

Answer 5

Oral replacement with cyanocobalamin unless the deficiency is severe

Question 6

How to treat concurrent Vitamin B12 and folate deficiency?

Answer 6

Treat the B12 deficiency first before correcting the folate deficiency.

Treating patients with folic acid when they have a B12 deficiency can lead to subacute combined degeneration of the cord.