Macrocytic Anaemia

Question 1

What are the main differential diagnoses for macrocytic anaemia?

Answer 1

• B₁₂ deficiency
• Folate deficiency
• Antifolate drugs
• Alcohol abuse
• Hepatitis and liver disease
• Hypothyroidism
• Haemolysis
• Myelodysplasia

Question 2

What might cause B₁₂ deficiency?

Answer 2

• Pernicious anaemia
• Intestinal malabsorption

Question 3

What suggests that B₁₂ deficiency is the cause of macrocytic anaemia?

Answer 3

• Associated autoimmune disease, e.g. primary hypothyroidism, vitiligo etc
• Decreased WCC
• Decreased platelets

Question 4

What confirms that B₁₂ deficiency is the cause of macrocytic anaemia?

Answer 4

Decreased serum B₁₂. with or without decreased folate

Question 5

What does pernicious anaemia need to be diagnosed in the absence of?

Answer 5

Any general malabsorption

Question 6

How is pernicious anaemia managed?

Answer 6

Hydroxycobalamin 1mg IM every 3-4months after loading dose

Question 7

What suggests that folate deficiency is the cause of macrocytic anaemia?

Answer 7

• Poor diet
• Prengnacy
• Lactation
• General malabsorption

Question 8

What confirms that folate deficiency is the casue of macrocytic anaemia?

Answer 8

Decreased serum folate, but serum B₁₂ normal

Question 9

How is folate deficiency managed?

Answer 9

• Eliminate cause
• Folic acid 5mg daily for 4 months. Correct any B₁₂ deficiency before giving folic acid

Question 10

Give three examples of anti-folate drugs that might cause macrocytic anaemia

Answer 10

• Phenytoin
• Barbituates and similar
• Methotrexate and similar

Question 11

What confirms that antifolate drugs are the cause of macrocytic anaemia?

Answer 11

Response to high dose folic acid treatment, or stopping drug

Question 12

What suggests that alcohol abuse is the cause of macrocytic anaemia?

Answer 12

History

Question 13

What confirms that alcohol abuse is the cause of macrocytic anaemia?

Answer 13

Response to abstinence

Question 14

What suggests that hepatitis and liver disease are the casue of macrocytic anaemia?

Answer 14

Abnormal liver enzymes

Question 15

What confirms that hepatitis and liver disease is the cause of macrocytic anaemia?

Answer 15

• Normal or increased serum B₁₂
• Poor response to folic acid

Question 16

What suggests that hypothyroidism is the cause of macrocytic anaemia?

Answer 16

Decreased FT4 and increased TSH

Question 17

What confirms that hypothyroidism is the cause of macrocytic anaemia?

Answer 17

• Normal B₁₂ ​
• Response to treatment with thyroxine

Question 18

How is hypothyroidism managed?

Answer 18

Levothyroxine replacement, e.g. 25-50mg/day, adjust based on TSH

Question 19

What suggests that haemolysis is the cause of macrocytic anaemia?

Answer 19

Urobilinogen in urine

Question 20

What confirms that haemolysis is the cause of macrocytic anaemia?

Answer 20

• Increased reticulocytes on blood film
• Decreased haptoglobin

Question 21

How is haemolysis managed?

Answer 21

• Avoid precipitating factors
• Blood transfusion if anaemia is severe
• Definitive treatment depends on cause, e.g. steroid and immunosupressants in autoimmune haemolytic anaemia

Question 22

What suggests that myelodysplasia is the cause of macrocytic anaemia?

Answer 22

Hepato- or splenomegaly

Question 23

What confirms that myelodysplasia is the cause of macrocytic anaemia?

Answer 23

• Bone marrow examination
• Normal B₁₂ and folate
• Pancytopenia in later stages

Question 24

How is myelodysplasia managed?

Answer 24

• Intensive combination or single-agent chemotherapy
• Frequent transfusion of RBC and platelets
• Stem cell transfusion if young patient