Polycythaemia vera

Question 1

What is polycythaemia vera also known as?

Answer 1

Polycthaemia rubra vera (PRV)

Question 2

What is PV?

Answer 2

This is a form of MPN, resulting in high haemoglobin and haematocrit, accompanied by a true increase in red cell mass

It can cause excessive production of other lineages

Question 3

What is the most common cause of PV?

Answer 3

This is most commonly caused by a mutation in JAK2

This is a kinase mutation present in over 95% of PV cases

The mutation results in abnormal signalling, so activation of erythropoiesis can occur in absence of a ligand, resulting in overproduction of red cells

Question 4

What are some unique symptoms of PV (As well as general)?

Answer 4

• Headache
• Aquagenic pruritus (Itching on contact with hot water)

Question 5

What is aquagenic pruritus?

Answer 5

Itching on contact with hot water

Question 6

What are some conditions that may be mistaken for PV?

Answer 6

Secondary polycythaemia
Pseudopolycythaemia

Question 7

What are some causes of secondary polycythaemia?

Answer 7

Chronic hypoxia
Carbon monoxide poisoning
Cyanide poisoning
Smoking
Erythropoietin-secreting tumours

Question 8

What causes pseudopolycthaemia?

Answer 8

a decrease in plasma volume, causing analysis to detect a high red cell proportion

This can be caused by dehydration, diuretic therapy and obesity

Question 9

What are some tests required in PV?

Answer 9

• History
• Examination (e.g. splenomegaly)
• FBC
• JAK2 mutational analysis
• CXR, O2 sats, drug history
• EPO levels and bone marrow biopsy (not common)

Question 10

How is PV managed?

Answer 10

• Venesection to haematocrit <0.45
• Aspirin
• Cytotoxic oral chemotherapy (e.g. hydroxycarbamide)
• Interferon, JAK inhibitor (Rexolitinib)