Macrocytic Anaemia

Question 1

What is macrocytic anaemia?

Answer 1

Anaemia associated with a high MCV of erythrocytes (> 100 fl in adults)

Question 2

What are the 2 types of macrocytic anaemia?

Answer 2

Megaloblastic

Non-megaloblastic

Question 3

What is megaloblastic anaemia?

Answer 3

Bone marrow produces unusually large, structurally abnormal, immature red cells

Question 4

What causes megaloblastic anaemia?

Answer 4

B12 or folate deficiency

Required for conversion of deoxyuridate to thymidylate, DNA synthesis + nuclear maturation

Question 5

List 4 causes of B12 deficiency

Answer 5

Reduced intake (vegans)
Reduced absorption post-op eg, gastrectomy or ileal resection.
Reduced absorption: Pernicious anaemia.
Abnormal metabolism (congenital transcobalamin II deficiency)

Question 6

List 5 causes of folate deficiency

Answer 6

Reduced intake (alcoholics, elderly, anorexia) 
Increased demand (pregnancy, malignancy)
Reduced absorption
Jejunal disease (e.g. coeliac)  
Drugs (e.g. phenytoin)

Question 7

List 8 causes of non megaloblastic macrocytic anaemia

Answer 7

Alcohol excess  
Liver disease   
Hypothyroidism  
Haemolysis (reticulocytosis)  
Aplastic anaemia
Myelodysplasia
Multiple myeloma.
Drugs

Question 8

Give 2 facts on the epidemiology of macrocytic anaemia

Answer 8

More common in ELDERLY FEMALES

Pernicious anaemia= MOST COMMON cause of B12 deficiency in the West

Question 9

What are 5 presenting symptoms of macrocytic anaemia?

Answer 9

SOBOE
Fatigue.
Palpitations.
Exacerbation of angina.
Symptoms of the CAUSE (e.g. weight loss, diarrhoea)

Question 10

What 2 things in the history may be relevant in a patient with suspected macrocytic anaemia?

Answer 10

FH of AI disease

Previous GI surgery

Question 11

List 3 signs of anaemia

Answer 11

Pallor.
Tachycardia
Breathlessness

Question 12

List 4 signs of pernicious anaemia

Answer 12

Mild jaundice
Glossitis
Angular stomatitis
Weight loss

Question 13

List 5 signs of B12 deficiency

Answer 13

Peripheral neuropathy  
Ataxia  
Subacute combined degeneration of the spinal cord  
Optic atrophy  
Dementia

Question 14

List 4 features to assess on a FBC in macrocytic anaemia

Answer 14

High MCV
Pancytopaenia in megaloblastic anaemia
Different degrees of cytopaenia in myelodysplasia
Exclude reticulocytosis

Question 15

What may be seen on an LFT in macrocytic anaemia?

Answer 15

High BR (due to ineffective erythropoiesis or haemolysis)

Question 16

List 4 other blood tests would you perform in suspected macrocytic anaemia

Answer 16

Serum vitamin B12
Red cell folate
Anti-parietal cell + anti-IF antibodies
Serum protein electrophoresis: looking for a dense band in myeloma

Question 17

What is seen on the blood film in Macrocytosis? What about megaloblastic anaemia?

Answer 17

Large erythrocytes

In megaloblastic: Megaloblasts + Hypersegmented neutrophil nuclei

Question 18

What does the Schilling test identify ?

Answer 18

Pernicious anaemia

B12 will only be absorbed when given with IF

Question 19

How is folate deficiency managed?

Answer 19

Oral folic acid

If B12 deficiency is present, it must be treated before the folic acid deficiency

Question 20

What does pernicious anaemia increase the risk of?

Answer 20

Gastric cancer

Question 21

What does folate deficiency in pregnancy increase the risk of?

Answer 21

Neural tube defects

Question 22

Why must B12 deficiency be treated before folate deficiency?

Answer 22

Treating folate deficiency 1st may aggravate the B12 deficiency + precipitate subacute combined degeneration of the cord.

Question 23

What is the approach to management of Macrocytosis?

Answer 23

Correcting the deficiency that has caused macrocytosis, with or without anaemia.
Treating underlying condition that led to the deficiency

Question 24

What is pernicious anaemia?

Answer 24

AI loss of parietal cells +/or intrinsic factor, thus preventing absorption of B12

Question 25

How is pernicious anaemia managed?

Answer 25

Hydroxycobalamin B12 injections

Question 26

List 4 drugs that can cause macrocytic anaemia

Answer 26

Methotrexate (dihydrofolate reductase inhibitor)
Hydroxyurea
Azathioprine
Zidovudine