Macrocytosis and microcytic anaemia

Question 1

What does MCV stand for?

Answer 1

Mean Corpuscular (cellular) volume

Question 2

What unit of measurement is used for MCV?

Answer 2

Femtolitres

Question 3

What is the normal MCV?

Answer 3

80-100 fl

Question 4

WHat is macrocytic MCV?

Answer 4

> 100fl

Question 5

Name 2 causes of macrocytosis?

Answer 5

megaloblastic

Non-megaloblastic

Question 6

What does megaloblastic mean?

Answer 6

An abnormally large nucleated red cell precursor with an immature nucleus

Question 7

How are megaloblastic anaemias characterised?

Answer 7

Predominant defects in DNA synthesis and nuclear maturation with relative preservation of RNA and haemoglobin synthesis

Question 8

What causes the red cell to be bigger than normal?

Answer 8

The nucleus is still immature

Question 9

Is the larger size of a red cell due to it growing too big?

Answer 9

No, but its failure to become smaller

Question 10

Name 4 causes of megaloblastic anaemia

Answer 10

B12 deficiency
Folate deficiency
Drugs
Rare inherited abnormalities

Question 11

What are B12 and folate essential for?

Answer 11

Nuclear maturation

Enable chemical reactions that provide enough nucleosides for DNA synthesis

Question 12

What does the methionine cycle produce?

Answer 12

s-adenosyl methionine, a methyl donor to DNA, RNA, proteins, lipids, folate intermediates.

Question 13

What is folate cycle important for?

Answer 13

Nucleoside synthesis (i.e. uridine to thymidine conversion

Question 14

What are dietary folates converted to?

Answer 14

Monoglutamate

absorbed in jejunum

Question 15

What are the sources of B12 and folate?

Answer 15

B12 - animal

Folate - leafy veg, yeast destroyed by cooking

Question 16

What is the body store time for B12 and folate?

Answer 16

B12 - 2-4 years

Folate - 4 months

Question 17

Where are B12 and folate absorbed?

Answer 17

B12 - Ileum

Folate - Duodenum and jejunum

Question 18

What is the daily requirement of B12 and folate?

Answer 18

B12 - 1-3ug/day

Folate - 100ug/day

Question 19

What malabsorption disorders can cause folate deficiency?

Answer 19

Coeliac

Crohn’s

Question 20

What can cause folate deficiency via excess utilisation?

Answer 20

Haemolysis
Exfoliating dermatitis
Pregnancy
Malignancy

Question 21

What drugs can cause folate deficiency?

Answer 21

Anticonvulsants

Question 22

What clinical features are present in both B12 deficiency and folate deficiency?

Answer 22

Symptoms/signs of anaemia
Weight loss, diarrhoea, infertility
Sore tongue, jaundice
Developmental problems

Question 23

What are some clinical features specific to B12 deficiency and not present in folate deficiency?

Answer 23

Neurological problems - posterior/dorsal column abnormalities
Neuropathy, dementia, psychiatric issues

Question 24

What is pernicious anaemia?

Answer 24

Autoimmune condition with resulting destruction of gastric parietal cells

Question 25

What is pernicious anaemia associated with?

Answer 25

Atrophic gastritis

Personal/FHx of autoimmune disorders (e.g. addisons, hypothyroidism, vitiligo)

Question 26

What autoantibodies should be checked for?

Answer 26

Anti gastric-parietal cell (GPC)

Anti-intrinsic factor (IF)

Question 27

What is a treatment for megaloblastic anaemia?

Answer 27

Vit B12 injections (pernicious anaemia)
Folic acid tablets (5mg OD PO)
If life threatening - transfuse red cells

Question 28

What are causes of non-megaloblastic macrocytosis?

Answer 28

Alcohol
Liver disease
Hypothyroidism
Marrow failure

Question 29

Name 3 serious issues that are associated with anaemia?

Answer 29

Myelodysplasia
Myeloma
Aplastic anaemia

Question 30

What is inneffective erythropoiesis?

Answer 30

Red cells die prematurely in the marrow.
Haem and lactate dehydrogenase are released from dead red cells
haem converted to biliruben