Macrocytic anaemias

Question 1

What is released by the salivary glands for B12 absorption and what is its importance?

Answer 1

Haptocorrin/transcobalamin I (TCN1)

Protects vitamin B12 from acid digestion

Question 2

What degrades Haptocorrin/transcobalamin I (TCN1)?

Answer 2

Pancreatic proteases in duodenum

Question 3

What allows absorption of B12 in the terminal ileum?

Answer 3

Intrinsic factor

Question 4

What are the causes of B12 deficiency?

Answer 4

1. Nutritional (vegan, poor diet, pregnancy)
2. Malabsorption
   Gastric (Surgery, pernicious anaemia)
   Intestine (Ileal resection, fish tapeworm and tropical sprue)
3. Get malabsorption of B12 but not deficiency in Crohn’s disease, Coeliac, CF

Question 5

What are the symptoms associated with B12 deficiency?

Answer 5

• Gradual onset
• ‘Lemon tinge’ due to pallor (anaemia) and mild jaundice (haemolysis)
• Glossitis (inflammation of the tongue)
• Angular cheilitis (inflammation of the corners of the mouth)
• Neuropathy

Question 6

What is pernicious anaemia?

Answer 6

Autoimmune condition where atrophic gastritis leads to reduced secretion of IF from parietal cells of the stomach.

Dietary B12 remains unbound and cannot be absorbed by terminal ileum.

Question 7

What diagnoses B12 deficiency?

Answer 7

• Low Hb
• High MCV
• Low serum B12/cobalamin
• Low reticulocytes
• Hypersegmented neutrophils (5+ lobes)
• Low WCC and platelets if severe

Question 8

What diagnoses pernicious anaemia?

Answer 8

• IF antibodies (more sensitive)

* Parietal cell antibodies

Question 9

How do you treat B12 deficiency?

Answer 9

MALABSORPTION
- Hydroxocobalamin injections
Given frequently until B12 restored and then every 2-3 months

DIET
-Oral cyanocobalamin

Question 10

What can cause folate deficiency?

Answer 10

1. Nutritional (Poor diet, goat’s milk only)
2. Intestinal (Coeliac, jejunal resection)
3. Excessive requirement (Pregnancy, prematurity)
4. Increased turnover (Chronic haemolysis, severe skin disease)
5. Drugs (Methotrexate, anticonvulsants)
6. Excess low (Dialysis)
7. Miscellaneous (Alcohol)

Question 11

How do you diagnose folate deficiency?

Answer 11

Serum folate <7 nanomol/L

Question 12

How do you treat folate deficiency?

Answer 12

Folic acid 5mg o.d. for 4 months

Question 13

What do you monitor after treatment has started for B12 and folate deficiency?

Answer 13

FBC and reticulocyte count in 7-10 days

• Risen above normal range = good
• No rise = check serum folate

8 weeks – measure iron and folate levels
- MCV should have normalised