Polycythaemia

Question 1

Define:

Answer 1

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

Question 2

What are the two classifications:

Answer 2

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

Question 3

Aetiology/risk factors:

Answer 3

• Polycythaemia Rubra Vera – primary cause (Mutations in JAK2 tyrosine kinase are involved – RBC form without EPO)

Secondary Polycythaemia – increase in EPO
o Appropriate increase in erythropoietin (Due to chronic hypoxia (e.g. chronic lung disease, living at high altitude))
o 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
o May be acute – due to dehydration (e.g. diuretics, burns, enteropathy, alcohol)
o Chronic form associated with obesity, hypertension, high alcohol and tobacco intake
o Gaisbock’s syndrome

Question 4

Epidemiology:

Answer 4

• Annual UK incidence: 1.5/100,000

* Peak age: 45-60 yrs

Question 5

Symptoms:

Answer 5

• Headaches
• Dyspnoea
• Tinnitus
• Blurred vision
• Pruritis after HOT BATH
• Burning sensation in fingers and toes (erythromelalgia)
• Night sweats
• Thrombosis (DVT, stroke)
• Pain from peptic ulcer disease
• Angina
• Gout
• Choreiform movements

Question 6

Signs:

Answer 6

• 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 7

Investigations for diagnosis:

Answer 7

•	Required for Diagnosis
o	FBC 
•	High Hb
•	High haematocrit 
•	Low MCV
•	Isotope Dilution Techniques
o	Allows confirmation of plasma volume and red cell mass 
o	Distinguishes between relative and absolute polycythaemia

Question 8

Investigations for polycthaemia ruba vera:

Answer 8

o	High Hb, RCC, HCT, PCV
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

Question 9

Investigations for secondary polycythaemia:

Answer 9

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