Macrocytic anaemia

Question 1

What are the 2 types of macrocytic anaemia?

Answer 1

1. Megaloblastic macrocytic anaemia.

2. Non-megaloblastic macrocytic anaemia.

Question 2

What is the difference between the 2 types of macrocytic anaemia?

Answer 2

The presence (or not) of megaloblasts.

Question 3

What does the mnemonic FAT RBC stand for?

Answer 3

· F - Folate deficiency.
· A - Alcohol.
· T - Thyroid (hypothyroidism). 
· R - Reticulocytosis.
· B - B12 deficiency/pernicious anaemia. 
· Cytotoxic drugs.

Question 4

Who is most commonly affected by pernicious anaemia?

Answer 4

Women aged 60+.

Question 5

What is the pathophysiology for megaloblastic macrocytic anaemia?

Answer 5

Larger than normal RBCs with immature nuclei.

Question 6

What is the pathophysiology for vitamin B12?

Answer 6

· B12 combines with IF, which is produced by parietal cells in the stomach, to form an IF-B12 complex.
· This complex binds to IF receptors in the ileum, which then allows B12 absorption.

Question 7

What is the pathophysiology for pernicious anaemia?

Answer 7

· An autoimmune process which affects the gastric mucosa, leading to atrophy.
· This atrophy reduces the number of parietal cells, which secrete IF (intrinsic factor).
· IF is essential for B12 absorption.

Question 8

What can happen if macrocytic anaemia is left untreated?

Answer 8

Neurological changes can occur and be irreversible.

Question 9

What are the causes of vitamin B12 deficiency?

Answer 9

· Pernicious anaemia - reduced production of IF.
· Malabsorption - gastrectomy, Crohn’s, Vegan diet.
· Drugs - PPI’s, H2 receptor antagonists.

Question 10

What are the causes of folate deficiency?

Answer 10

· Coeliac disease.
· Alcoholism.
· Drugs - Alcohol, nitrofurantoin, methotrexate, trimethoprim.
· Excessive urinary excretion.

Question 11

What are the 3 aetiologies of macrocytic anaemia?

Answer 11

1. Vit B12 deficiency.
2. Folate deficiency.
3. Drugs - e.g. immunosuppressants.

Question 12

When do symptoms typically develop?

Answer 12

Develops insidiously and may not cause symptoms until anaemia is severe.

Question 13

What anaemia symptoms occur?

Answer 13

· Breathlessness on exertion.
· Tiredness.
· Palpitations.
· Pallor.

Question 14

What GI manifestations occur?

Answer 14

· Diarrhoea.
· Glossitis.
· Anorexia.

Question 15

What neuro manifestations, with vit B12 deficiency, occur?

Answer 15

· Peripheral neuropathy.
· Loss of vibration sense and proprioception.
· Gait instability.
· Dementia.

Question 16

What investigations would you request if you suspected a patient had macrocytic anaemia? What would the results typically show?

Answer 16

· FBC - low haemoglobin and high MCV. 
· Reticulocytes - ;ow. 
· Blood smear. Diagnosis is usually based on this:
 - Macrocytic. 
 - MCV >100fL/cell. 
· B12 levels - low. 
· Folate levels - low. 
· Iron levels.

Question 17

Suggest some differentials.

Answer 17

· Alcoholic liver disease.
· Myelodysplastic syndromes.
· Newborn. 
· Hypothyroidism. 
· Reticulocytosis.

Question 18

What are the treatment options for B12 deficient patients?

Answer 18

· If neuro involvement - seek haematology advice.
· IM B12 injections.
· Dietary advice - eggs, meat, milk, dairy, salmon and cod.

Question 19

What are the treatment options for folate deficient patients?

Answer 19

· Prescribe oral folic acid 5mg daily.
· Check B12 levels in all people starting folic acid.
· Dietary advice - asparagus, broccoli, brown rice, brussels sprouts, chickpeas and peas.

Question 20

What B12 deficiency complications can occur?

Answer 20

· Neurological changes.
· Infertility (temporary).
· Stomach cancer with pernicious anaemic.
· Neural tube defects in pregnancy.

Question 21

What folate deficiency complications can occur?

Answer 21

· Infertility (temporary). 
· CVD. 
· Cancer. 
· Pre-term birth in pregnancy. 
· Neural tube defects in pregnancy.