Polycythaemia

Question 1

Definition

Answer 1

An increase in haemoglobin concentration above the upper limit of normal for a
person’s age and sex.

Classified into:
o Relative Polycythaemia = normal red cell mass but low plasma volume
o Absolute (True) Polycythaemia = increased red cell mass

Question 2

Aetiology (polycythaemia rubra vera)

Answer 2

Polycythaemia Rubra Vera

o Characterised by clonal proliferation of myeloid cells
o They have varied morphologic maturity and haematopoietic efficiency
o Mutations in JAK2 tyrosine kinase are involved

Question 3

Aetiology (secondary polycythaemia)

Answer 3

o Appropriate increase in erythropoietin
• Due to chronic hypoxia (e.g. chronic lung disease, living at high altitude)
• This leads to upregulation of erythropoiesis

o Inappropriate increase in erythropoietin
• Renal (carcinoma, cysts, hydronephrosis)
• Hepatocellular carcinoma
• Fibroids
• Cerebellar haemangioblastoma
• Secondary polycythaemia may be due to erythropoietin abuse by athletes

Question 4

Aetiology (relative polycythaemia)

Answer 4

o Dehydration (e.g. diuretics, burns, enteropathy)

o Gaisbock’s syndrome
• Occurs in young male smokers with hypertension, which results in a decrease in plasma volume and an apparent increase in red cell count

Question 5

Epidemiology

Answer 5

• Annual UK incidence: 1.5/100,000

* Peak age: 45-60 yrs

Question 6

Presenting symptoms

Answer 6

• Headaches
• Dyspnoea
• Tinnitus
• Blurred vision
• Pruritis after hot bath
• Night sweats
• Thrombosis (DVT, stroke)
• Pain from peptic ulcer disease
• Angina
• Gout
• Choreiform movements

Question 7

Signs on physical examination

Answer 7

• Plethoric complexion (red, ruddy)
• Scratch marks from itching
• Conjunctival suffusion (redness of the conjunctiva)
• Retinal venous engorgement
• Hypertension
• Splenomegaly (in 75% of cases)
• Signs of underlying aetiology in secondary polycythaemia

Question 8

Investigations (for diagnosis)

Answer 8

Required for Diagnosis

o FBC
• High Hb
• High haematocrit
• Low MCV

Question 9

Investigations

Answer 9

• Isotope Dilution Techniques
o Allows confirmation of plasma volume and red cell mass
o Distinguishes between relative and absolute polycythaemia

• Polycythaemia Rubra Vera
o High WCC
o High platelets
o Low serum EPO
o JAK2 mutation
o Bone marrow trephine and biopsy shows erythroid hyperplasia and raised
megakaryocytes

• Secondary Polycythaemia
o High serum EPO
o Exclude chronic lung disease/hypoxia
o Check for EPO-secreting tumours