Polycythaemia

Question 1

Define polycythaemia

Answer 1

Increased haemoglobin (and haematocrit)
• Females >16.5 g/dL (>0.48)
• Males >18.5 g/dL (>0.52)
Relative – reduced plasma volume and normal red cell mass
True – increased red cell mass

Question 2

What are the causes/risk factors of polycythaemia?

Answer 2

Primary
• Polycythaemia rubra vera (JAK2V617F mutation)

Secondary
• Chronic hypoxia e.g. chronic lung disease -> ↑ erythropoietin
• Renal carcinoma, cysts, hydronephrosis
• Hepatocellular carcinoma
• Iatrogenic EPO abuse

Relative
• Dehydration e.g. diuretics, burns

Question 3

What are the symptoms of polycythaemia?

Answer 3

• Headaches
• Dyspnoea
• Tinnitus
• Blurred vision
• Pruritus after hot bath
• Night sweats
• Erythromelalgia (tenderness/painful burning of fingers, palms, heels and toes)
• Gout

Bleeding
• Peptic ulcer disease

Thrombosis
• DVT
• Stroke
• MI

Question 4

What are the signs of polycythaemia?

Answer 4

• Facial plethora
• Excoriation marks
• Hypertension
• Splenomegaly

Question 5

What investigations are carried out for polycythaemia?

Answer 5

• FBC - elevated Hb (>16.5 g/dL in females, >18.5 g/dL in males)
- Elevated Hct (>48% in females, >52% in males)
- Low MCV, often co-existent with iron deficiency.
- PV is also associated with leucocytosis and thrombocytosis.
• LFTs - commonly normal unless there is polycythaemia due to HCC.
• Isotope Dilution Techniques - using infusion of radiolabelled albumin (131I) and RBCs (51Cr) allow confirmation of plasma volume and red cell mass (RCM) and distinguish between relative and absolute polycythaemia.
• PRV - leucocytosis
- Thrombocytosis
- Low EPO
- JAK2 mutation is present in almost all, but is not specific to PV.
- bone marrow biopsy shows erythroid hyperplasia and elevated megakaryoctyes.
• Secondary Polycythaemia - high EPO
- CXR, ABG and Pulse oximeter to exclude hypoxia and CLD.
- Abdominal CT/ Brain MRI to search for EPO-producing tumour