Macrocytic Anaemia

Question 1

What are the causes of Megaloblastic Anaemia?

Answer 1

▪️Folate deficiency

▪️Vitamin B12 deficiency

Question 2

What is a Megaloblast?

Answer 2

Large cells where the nucleus is immature (undeveloped) in comparison to the cell cytoplasm.
This is due to impaired DNA synthesis.

Question 3

Where is vitamin B12 absorbed?

Answer 3

The terminal ileum

Question 4

Where is vitamin B12 stored?

Answer 4

The liver

Question 5

Where is Intrinsic factor produced?

Answer 5

The parietal cells of the stomach

Question 6

What is the role of intrinsic factor?

Answer 6

IF is involved in the absorption of vitamin B12

Question 7

What is pernicious anaemia?

Answer 7

The production of antibodies against the parietal cells of the stomach, preventing the absorption of vitamin B12.

Pernicious anaemia is also associated with achlorhydria, as the parietal cells no longer produce acid.

Characteristics of pernicious anaemia include: yellow skin and a beefy tongue

Question 8

Where is vitamin B12 found in the diet?

Answer 8

Meat and dairy products.

Vegetarians suffer from B12 deficiency.

Question 9

What is the main role of vitamin B12?

Answer 9

Vitamin B12 is involved in the synthesis of thymidine and therefore DNA synthesis.

Question 10

Why is pernicious anaemia treated with oral B12, when the vitamin requires IF for absorption?

Answer 10

99% of cobalamin is absorbed bound to IF.

1% of cobalamin is absorbed passively and unbound.

Question 11

What is the broad classification of Macrocytic anaemia?

Answer 11

Megaloblastic anaemia and Non-megaloblastic anaemia

Question 12

What effect does B12 deficiency have on the nervous system?

Answer 12

▪️Weakness
▪️Paraesthesia
▪️Gait abnormalities

Question 13

List the causes of B12 deficiency

Answer 13

▪️Pernicious anaemia
▪️Malabsorption e.g. Gastrectomy, terminal ileal resection, Crohn’s disease, bacterial overgrowth, tape worm
▪️Vegetarian diet

Question 14

What foods are rich in folate?

Answer 14

▪️Green vegetables
▪️Yeast
▪️Nuts
▪️liver

Question 15

Name some drugs that act as folate antagonists, and therefore lead to folate deficiency.

Answer 15

▪️Methotrexate
▪️Sulphonamides
▪️Trimethoprim
▪️Phenytoin
▪️Sodium valproate

Question 16

Where is folate stored?

Answer 16

The liver

Question 17

Where is folate absorbed?

Answer 17

The duodenum and ileum

Question 18

What dose of folic acid is taken during pregnancy?

B) When is folic acid first started and how long is it taken in pregnancy?

Answer 18

400 micrograms
5mg in women with high risk of having a baby with a neural tube defect.

B) Started before conception and until 12 weeks of pregnancy

Question 19

What do low levels of folic acid do to the levels of homocysteine?

Answer 19

🔽Folic acid causes an ⬆️ in homocysteine levels

Question 20

What is the role of folate?

Answer 20

Folate, via tetrahydrofolate transfers one carbon compounds to purine rings to form the bases involved in the synthesis of DNA.

Question 21

What are the causes of NON MEGALOBLASTIC, macrocytic anaemia?

Answer 21

▪️Alcohol
▪️Hypothyroidism 
▪️Pregnancy
▪️Liver disease
▪️Reticulocytosis