Vitamin B12 Deficiency + Pernicious Anaemia

Question 1

Classic symptom pattern for B12 deficiency?

Answer 1

Macrocytic anaemia
Glossitis
Peripheral neuropathy

Question 2

Causes of B12 deficiency?

Answer 2

• Pernicious anaemia
• Poor dietary intake
• Malabsorption secondary to disease of the terminal ileum

Question 3

What is pernicious anaemia?

Answer 3

Autoimmune loss of parietal cells and/or intrinsic factor

- prevents absorption of B12 (needs IF)

Question 4

What antibodies do patients often have in pernicious anaemia and what is their specificity for it?

Answer 4

90% have anti-parietal antibodies (not specific, some normal women also have it)
60% have anti-IF antibodies (much more specific marker)

Question 5

Common complaints for pernicious anaemia?

Answer 5

Lethargy

General malaise

Question 6

How does bowel pathology cause B12 deficiency?

Answer 6

Those with bowel pathology (e.g. Crohn’s) have normal IF levels, but cannot absorb the B12-IF complex due to the disease of the terminal ileum

Question 7

Specific features of B12 deficiency?

Answer 7

Peripheral neuropathy
Smooth tongue
Angular stomatitis
Depression
Dementia
Subacute degeneration of the spinal cord

Question 8

Blood film results of B12 deficiency?

Answer 8

Microcytic (raised MCV) megaloblastic anaemia (RBC precursors with nuclei)
Hypersegmented neutrophil nuclei (>6 lobes)

Question 9

Blood test results of B12 deficiency?

Answer 9

Vit B12 is low

Ferritin levels normal (= normal iron stores)

Question 10

What test is done to distinguish pernicious anaemia from intestinal causes of B12 deficiency?

Answer 10

Two-part Schilling test

Question 11

Treatment of B12 deficiency?

Answer 11

Hydroxocobalamin (IM prep of B12)

• 1mg every other day until blood film/symptoms improve
• 1 mg injections every 3 months after