Polycythaemia Flashcards
What is polycythaemia?
- An increase in Hb and
- Increase in PCV - packed cell volume (haematocrit) / Increased RCC - I.E. too many RBCs
PCV = % by volume of RBCs in blood.
In polycythaemia rubra vera, what is there an excess proliferation of?
Red cells, white cells and platelets - hyperviscosity/hypervolaemia.
It’s a clonal haematopoietic disorder w/ erythrocytosis, thrombocytosis, leucocytosis + splenomegaly.
What gene mutation causes polycythaemia rubra vera?
JAK2 - V617F somatic mutation.
Ph negative (Philadelphia Chromosome)
Name a primary cause of polycythaemia.
Polycythaemia rubra vera - over reactive BM
- Malignant proliferation of a clone from 1 pluripotent marrow stem cell - myeloproliferative disorder of predominantly red cells.
Give 3 secondary causes of polycythaemia.
Due to hypoxia.
1. Heavy smoking.
2. Lung disease.
3. Cyanotic heart disease.
4. High altitude.
What is the difference between relative and absolute polycythaemia?
Relative = low plasma volume, but no change in cell numbers.
Absolute = increase in RBC mass.
Who gets relative polycythaemia?
Middle aged obese males, smokers, high alcohol intake, hypertension
Give 3 vague presenting symptoms of polycythaemia and why may present.
Due to hyperviscosity.
- Itching.
- Headache.
- Dizziness/Tiredness.
- Visual disturbance.
- Tinnitus.
Give 3 specific symptoms of polycythaemia.
Features of thrombosis/bleeding e.g. stroke, PE, MI, DVT
- Severe itching after a hot bath / when the patient is warm
- Erythromelalgia – burning sensation in fingers + toes
- Gout
- Hypertension
- Angina
- Intermittent claudication
- Plethoric complexion – congested / swollen with blood in facial skin
Why do polycythaemia patients get gout?
Increased urate from RBC turnover
What 3 blood test values would be increased in someone with polycythaemia?
- Hb.
- RCC.
- PCV.
What symptoms distinguishes PV from secondary causes?
Hepatosplenomegaly
- Due to extramedullary haemopoiesis
What investigations would you carry out to diagnose polycythaemia?
- Full Blood count
- Raised WCC (white cell count) + platelets = for PV = distinguishes PV from other secondary causes - Raised Hb – major criteria
- Genetic screening
- JAK2 mutation present – major criteria - BM biopsy (minor criteria)
- Prominent erythroid, granulocytic + megakaryocytic proliferation - Low serum erythropoietin (minor criteria)
What will the BM of a patient with polycythaemia rubra vera show?
Hypercellularity with erythroid hyperplasia - “trilineage growth”
Outline the treatment for primary and secondary polycythaemia.
- If a secondary cause, treat the underlying cause.
- If a primary cause, treatment aims to maintain a normal blood count and prevent complications e.g. aspirin.
