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Year 3 > Polycythaemia (CH) > Flashcards

Polycythaemia (CH) Flashcards

1
Q

Define polycythaemia.

A

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

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2
Q

What is relative polycythaemia?

A

Normal red cell mass but low plasma volume

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3
Q

What can cause relative polycythaemia? (3)

A
  • dehydration
  • stress
  • Gaisbock’s syndrome (younger male smokers with increased vasomotor tone and hypertension)
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4
Q

What is true polycythaemia?

A

Increased red cell mass

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5
Q

What is polycythaemia vera?

A

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

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6
Q

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

A

Budd-Chiari syndrome

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7
Q

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

A

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

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8
Q

What can polycythaemia vera lead to? (4)

A
  • acute myeloid leukaemia
  • myelofibrosis
  • thrombosis
  • haemorrhage
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9
Q

What cells are increased in polycythaemia?

A

RBCs, WBCs and platelets

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10
Q

What contributes to hyperviscosity of blood in polycythaemia vera?

A

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

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11
Q

What is secondary polycythaemia?

A

Driven by excess EPO (appropriately or inappropriately increased)

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12
Q

What causes an appropriate increase in EPO in secondary polycythaemia?

A

Due to chronic hypoxia:

  • chronic lung disease e.g. COPD
  • living at high altitude
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13
Q

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

A
  • hepatocellular carcinoma
  • renal carcinoma
  • EPO abuse by athletes
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14
Q

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

A

Increased risk of thrombosis

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

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15
Q

What group does polycythaemia usually affect?

A

Disease of middle and older age

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16
Q

What are the clinical features of polycythaemia? (9)

A
  • 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
17
Q

What is the triad of hyperviscosity syndrome seen in polycythaemia?

A
  • mucosal bleeding
  • neurological symptoms (dizziness, headaches)
  • visual changes
18
Q

What are some risk factors for polycythaemia? (7)

A
  • age >40
  • Budd-Chiari syndrome
  • affected family member
  • JAK2 mutations
  • smoking
  • sleep apnoea
  • lung diseases
19
Q

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

A
  • Hb
  • Hct
  • WBC
  • platelets
  • MCV
  • LFTs
  • JAK2 mutation screen
20
Q

What happens to Hb in polycythaemia?

A

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

21
Q

What happens to Hct in polycythaemia?

A

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

22
Q

What happens to platelet count in polycythaemia?

A

Elevated due to thrombocytosis

23
Q

How can we differentiate between polycythaemia vera and secondary polycythaemia?

A

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

24
Q

What is a screen you would do for polycythaemia vera?

A

JAK2 gene mutation screen

25
Q

What do investigations show for polycythaemia vera? (5)

A
  • 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
26
Q

What other features are seen in polycythaemia vera?

A

Low ESR and raised leukocyte alkaline phosphatase

27
Q

What are some differential diagnoses for polycythaemia? (2)

A
  • essential thrombocytosis - normal EPO, isolated thrombocytosis absence of elevated Hb/red cell mass
  • chronic myelogenous leukaemia - thrombosis much less common, screen for Philadelphia chromosome
28
Q

How do we diagnose JAK2-positive polycythaemia vera?

A

High HCt OR raised cell mass
PLUS JAK2 mutation

29
Q

How do we diagnose JAK2-negative polycythaemia vera?

A

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)

30
Q

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

A
  • 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
31
Q

How do we specifically manage polycythaemia vera?

A
  • low-dose aspirin
  • phlebotomy for all patients (remove blood)
  • high-risk patients (>65, prior thrombosis) also receive cytoreductive therapy (hydroxycarbamide)
32
Q

How do we manage secondary polycythaemia?

A

Treat underlying cause

33
Q

How do we manage relative polycythaemia? (3)

A
  • fluid repletion
  • stop smoking
  • reduce use of caffeine-containing beverages, diuretics
34
Q

What are some complications of polycythaemia? (4)

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

Year 3 (148 decks)

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