Polycythaemia (CH) Flashcards by Savita Ramkumar

Define polycythaemia.

Increase in Hb concentration above upper limit of normal for age and sex

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What is relative polycythaemia?

Normal red cell mass but low plasma volume

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What can cause relative polycythaemia? (3)

dehydration
stress
Gaisbock’s syndrome (younger male smokers with increased vasomotor tone and hypertension)

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What is true polycythaemia?

Increased red cell mass

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What is polycythaemia vera?

Chronic myeloproliferative neoplasm (haematopoietic stem-cell proliferation) characterised by an erythropoietin-independent, irreversible increase in erythrocyte, granulocyte and platelet counts

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Name a condition that is a risk factor for polycythaemia vera?

Budd-Chiari syndrome

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What mutation is present in 95% of cases of polycythaemia vera?

JAK2 V617F (but not specific - present in other myeloproliferative neoplasms, AML, CML)

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What can polycythaemia vera lead to? (4)

acute myeloid leukaemia
myelofibrosis
thrombosis
haemorrhage

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What cells are increased in polycythaemia?

RBCs, WBCs and platelets

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What contributes to hyperviscosity of blood in polycythaemia vera?

Increased RBC mass and/or haematocrit + increased activated WBCs that release pro-inflammatory markers + neutrophil extracellular traps (NETs)

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What is secondary polycythaemia?

Driven by excess EPO (appropriately or inappropriately increased)

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What causes an appropriate increase in EPO in secondary polycythaemia?

Due to chronic hypoxia:

chronic lung disease e.g. COPD
living at high altitude

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What are some examples of inappropriate increase in EPO in secondary polycythaemia? (3)

hepatocellular carcinoma
renal carcinoma
EPO abuse by athletes

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What is there an increased risk of with elevated blood cell mass in polycythaemia?

Increased risk of thrombosis

(elevated blood cell mass –> hyperviscosity –> slow blood flow and increased thrombosis risk)

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What group does polycythaemia usually affect?

Disease of middle and older age

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What are the clinical features of polycythaemia? (9)

headache (fullness in head/neck, dizziness, perspiration)
fatigue/generalised weakness
pruritus (worse when skin contacts warm water)
features of thrombosis (DVT, stroke, angina/MI, PE, PVD)
night sweats
bone pains
erythromelalgia (tenderness/painful burning and/or redness of fingers, palms, heels, toes, face)
plethora (facial redness)
splenomegaly

What is the triad of hyperviscosity syndrome seen in polycythaemia?

mucosal bleeding
neurological symptoms (dizziness, headaches)
visual changes

What are some risk factors for polycythaemia? (7)

age >40
Budd-Chiari syndrome
affected family member
JAK2 mutations
smoking
sleep apnoea
lung diseases

What are the first-line investigations for polycythaemia? (7)

Hb
Hct
WBC
platelets
MCV
LFTs
JAK2 mutation screen

What happens to Hb in polycythaemia?

Elevated: >165g/L in men, >160g/L in women

What happens to Hct in polycythaemia?

Elevated: >52% in men, >48% in women

What happens to platelet count in polycythaemia?

Elevated due to thrombocytosis

How can we differentiate between polycythaemia vera and secondary polycythaemia?

Decreased serum EPO in polycythaemia vera, but increased in secondary polycythaemia

What is a screen you would do for polycythaemia vera?

JAK2 gene mutation screen

What do investigations show for polycythaemia vera? (5)

- WBC high - platelets high - JAK2 mutation present in almost all - LFTs elevated in Budd-Chiari syndrome --> portal/hepatic vein thrombosis screening - bone marrow biopsy - prominent erythroid, granulocytic and megakaryocytic proliferation with pleomorphic, mature megakaryocytes

What other features are seen in polycythaemia vera?

Low ESR and raised leukocyte alkaline phosphatase

What are some differential diagnoses for polycythaemia? (2)

- essential thrombocytosis - normal EPO, isolated thrombocytosis absence of elevated Hb/red cell mass - chronic myelogenous leukaemia - thrombosis much less common, screen for Philadelphia chromosome

How do we diagnose JAK2-positive polycythaemia vera?

High HCt OR raised cell mass PLUS JAK2 mutation

How do we diagnose JAK2-negative polycythaemia vera?

A1+A2+A3+either another A or two B criteria (Raised cell mass/Hct + absence of JAK2 mutation + no cause of secondary erythrocytosis + extra/s) (Low yield)

What are the different forms of management for polycythaemia? (4)

- phlebotomy (venesection) - mechanical reduction in number of RBCs - antiplatelet prophylaxis (aspirin) - prevent thrombotic events secondary to hyperviscosity - cytoreductive therapy (hydroxycarbamide/hydroxyurea) - mechanical reduction in RBCs - JAK2 inhibitors (Ruxolitinib) if everything fails

How do we specifically manage polycythaemia vera?

- low-dose aspirin - phlebotomy for all patients (remove blood) - high-risk patients (>65, prior thrombosis) also receive cytoreductive therapy (hydroxycarbamide)

How do we manage secondary polycythaemia?

Treat underlying cause

How do we manage relative polycythaemia? (3)

- fluid repletion - stop smoking - reduce use of caffeine-containing beverages, diuretics

What are some complications of polycythaemia? (4)

- thrombosis - may progress to AML or myelofibrosis - spent phase disease (increased BM fibrosis, splenomegaly) - haemorrhage