Polycythaemia

Question 1

Definition of polycythaemia

Answer 1

Is an increase in haemoglobin concentration.
Classified into:
Relative Polycythaemia:
◦ Reduced plasma volume, but normal RBC mass

		Absolute Polycythaemia:
						◦ Increased RBC mass
						◦ Split further into Primary and Secondary

Question 2

Aetiology of polycythaemia

Answer 2

• RELATIVE causes:
◦ Dehydration, high alcohol and tobacco intake

• PRIMARY causes:
◦ Polycythaemia Vera: Malignant proliferation of myeloid cells that results in erythrocytosis, thrombocytosis, leukocytosis and splenomegaly
◦ Caused by mutation in JAK2
◦ Increase in those cell types leads to greater risk of thrombosis and haemorrhage

• SECONDARY causes:
‣ Due to HYPOXIA:
◦ High altitudes, COPD, chronic lung diseases, heavy smoking
‣ Or due to inappropriate INCREASED ERYTHROPOIETEN production:
◦ Due to renal carcinoma or hepatocellular carcinoma

Question 3

History and Examination of polycythaemia

Answer 3

• Asymptomatic: finding can be incidental
• Headache
• Dizziness
• Weakness/fatigue
• Pruritus after hot bath/shower: severe itching especially after contact with warm water
• Facial redness
• Splenomegaly
• Tinnitus
• Features of thrombosis: stroke, DVT, PE etc
• Burning sensation at fingers and toes
• Visual disturbances
• Hypertension
• Hyperviscosity

Question 4

Risk factors for polycythaemia

Answer 4

• Age >40
• Family history
• Budd-chiari syndrome

Question 5

Investigations for polycythaemia

Answer 5

• FBC:
‣ Increased Hb
‣ Increased WBC
‣ Increased platelets
‣ Increased red cell count
• Haematocrit: Would be increased
• MCV: likely to be low
• JAK2 gene mutation screen: usually present
• Serum erythropoieten: likely reduced

Question 6

Treatment of polycythaemia

Answer 6

Low/intermediate risk of thrombosis: (likely <60 years old)
1) Phlebotomy: Blood is removed and replaced with saline twice weekly to bring down the haematocrit to 45%.

+ low dose Aspirin: take daily to reduce the risk of thrombosis without greatly increasing the risk of bleeding

+ Manage CVD risk factors: manage diabetes, Hyperlipidaemia and hypertension

High risk of thrombosis: (likely >60 years old)
1) Cytoreductive therapy:
‣ In the acute setting, HYDROXYCARBAMIDE is the first line drug.
‣ Is able to lower the haematocrit.
‣ Risk of pancytopenia
‣ There would then be phlebotomy long-term.

+ Low dose aspirin

Question 7

Complications of polycythaemia

Answer 7

• Thrombosis: likely due to hyperviscosity (e.g MI, stroke, DVT)
• Haemorrhage (unlikely)
• Pruritus

Question 8

Prognosis of polycythaemia

Answer 8

Variable prognosis, many remain well for years.
Main causes of mortality are CVD and transformation to acute myeloid leukaemia