Polycythaemia

Question 1

Define

Answer 1

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

Relative or absolute (true)

• Relative (↓plasma volume, normal RBC mass)
  
  • May be acute and due to dehydration (e.g. alcohol, diuretics, burns), or chronic (associated with obesity, HTN and ↑alcohol and tobacco intake)

Note: Gaisbock’s syndrome in young male smokers

• Absolute (↑RBC mass) – distinguished by RC mass estimation using radioactive chromium

Question 2

Causes

Answer 2

Polycythaemia Rubra Vera

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

Secondary Polycythaemia

• Appropriate increase in erythropoietin
  
  • Due to chronic hypoxia (e.g. chronic lung disease, living at high altitude)
  • This leads to upregulation of erythropoiesis
• Inappropriate increase in erythropoietin
  
  • Renal (carcinoma, cysts, hydronephrosis)
  • Hepatocellular carcinoma
  • Fibroids
  • Cerebellar haemangioblastoma
  • Secondary polycythaemia may be due to erythropoietin abuse by athletes
• Relative Polycythaemia
  
  • Dehydration (e.g. diuretics, burns, enteropathy)
  • 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 3

Epidemiology

Answer 3

Annual UK incidence 1.5/100 000

Peak age is 45–60 years.

Question 4

Symptoms

Answer 4

May be asymptomatic and detected on FBC Or may present with vague signs

 Headache, dizziness

 Dyspnoea

 Tinnitus, visual disturbance/blurred

 Itch after a hot bath

 Erythromelalgia

 Burning sensation in fingers and toes

Question 5

Signs

Answer 5

Facial plethora

 Splenomegaly

 ±Gout due to ↑urate form RBC turnover

 ±Features of arterial (cardiac, cerebral, peripheral) or

venous (DVT, cerebral, hepatic) thrombosis

Question 6

Investigations

Answer 6

Required for Diagnosis

FBC

• High Hb
• High haematocrit
• Low MCV

Isotope Dilution Techniques

• Allows confirmation of plasma volume and red cell mass
• Distinguishes between relative and absolute polycythaemia

Polycythaemia Rubra Vera

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

Secondary Polycythaemia

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