Polycythaemia vera

Question 1

Polycythaemia vera relates to lots of RBCs and is a myeloproliferative disorder caused by clonal proliferation of a marrow stem cells. What is the incidence of this condition?

1 - 200 per 100,000
2 - 20 per 100,000
3 - 2 per 100,000
4 - 0.2 per 100,000

Answer 1

3 - 2 per 100,000

Affects men and women equally

Question 2

Polycythaemia vera relates to lots of RBCs and is a myeloproliferative disorder caused by clonal proliferation of a marrow stem cells. What age does the incidence of this condition peak?

1 - 60-70
2 - 40-50
3 - 30-40
4 - 20-30

Answer 2

1 - 60-70

Question 3

Which of the following mutations accounts for 95% of patients with Polycythaemia vera?

1 - TP53
2 - MLH1 (Lynch syndrome)
3 - JAK2
4 - all of the above

Answer 3

3 - JAK2

Important gene, a non-receptor tyrosine kinase that is involved in the control hematopoietic growth factors, including erythropoietin (EPO).

Typically EPO from kidney binds to erythrocytes and triggers JAK2, but not here

Question 4

The JAK2 mutation is present in 95% of patients with Polycythaemia vera promoting erythroid progenitor cell proliferation and differentiation. Is this proliferation dependent on erythropoietin (EPO) levels?

Answer 4

• No

EPO levels are likely to be normal, which is the hallmark of PV

Question 5

What does haematocrit measure?

1 - O2 saturation in blood
2 - number of platelets in blood
3 - % of whole blood volume composed of RBCs
4 - haemoglobin levels in blood

Answer 5

3 - % of whole blood volume composed of RBCs

Question 6

In polycythaemia vera would we expect to see a raised or reduced haematocrit?

Answer 6

• increased

Normal = 0.37-0.5

Excessive activation of stem cells leads t their death and fibrosis tissue

Question 7

In polycythaemia vera there are increased RBCs, are WBCs and platelets affected?

Answer 7

• yes

Look for raised neutrophils, basophils and platelets

Not always but can be affected

Question 8

In polycythaemia vera we may see low RBCs, WBCs and platelets. Why does this occur?

1 - bone marrow becomes full of lymphoblasts
2 - bone marrow dies off due to overuse
3 - bone marrow becomes infected, killing off stem cells
4 - all of the above

Answer 8

2 - bone marrow dies off due to overuse

Referred to as the spent phase or Myelofibrosis

Question 9

Would we expect to see an increased or decreased ferritin in Polycythaemia vera?

Answer 9

• reduced

Increased RBC production will use up all iron and therefore deplete ferritin levels

Question 10

Polycythaemia vera can lead to hyperviscosity. Which of the following is this likely to lead to?

1 - deep vein thrombosis
2 - pulmonary embolism
3 - stroke or myocardial infarction
4 - organomegaly
5 - all of the above

Answer 10

5 - all of the above

Question 11

Which of the following is NOT a typical symptom of polycythaemia vera?

1 - Hyperviscosity
2 - Pruritus (after a hot bath)
3 - Organomegaly
4 - Haemorrhage
5 - Arthralgia
6 - Plethoric appearance
7 - Hypertension

Answer 11

5 - Arthralgia

Pruritus = likely to be due to excessive basophils and mast cells releasing histamines

Question 12

Which organ should be screened if a patient is suspected of having polycythaemia vera with no JAK2 mutation?

1 - liver
2 - kidneys
3 - spleen
4 - heart

Answer 12

2 - kidneys

Kidneys secret erythropoietin which stimulates RBC production, so it could be over secreting erythropoietin

Question 13

Which of the following medications is typically NOT used in the treatment of polycythaemia vera?

1 - Aspirin
2 - Clopidogrel
3 - Venesection
4 - Hydroxyurea
5 - Phosphorus-32 therapy

Answer 13

Aspirin = reduce risk of clotting
Venesection - first line treatment
Hydroxyurea = reduces RBCs and WBCs
Phosphorus-32 therapy = radiotherapy that targets bone marrow

Question 14

A 68-year-old male presented to the emergency department with lethargy and dyspnoea on exertion. He had a background medical history of polycythaemia rubra vera.

His full blood count was reported as follows:

Hb 84 g/L (Male: (135-180))
Platelets 46 * 109/L (150 - 400)
WBC 38.8 * 109/L (4.0 - 11.0)

What is the most likely diagnosis?

1 - Acute lymphoblastic leukaemia
2 - Acute myeloid leukaemia
3 - Chronic lymphocytic leukaemia
4 - Chronic myeloid leukaemia
5 - Infectious mononucleosis

Answer 14

2 - Acute myeloid leukaemia

Polycythaemia rubra vera - around 5-15% progress to myelofibrosis or AML

Question 15

A 62-year-old man presents with headaches. On examination he is found to have widespread bilateral expiratory wheeze on auscultation, facial plethora, heart rate 90 bpm, blood pressure 110/60 mmHg and SpO2 88%. He has a 60 pack year smoking history. He is currently treated with bendroflumethiazide and amlodipine for hypertension. Blood results show:

Haematocrit 0.58 (normal range 0.41-0.50)
RBC 8.8 * 1012/l (range 4-6 * 1012/l )

What is the most likely cause of the polycythaemia?

1 - Polycythaemia rubra vera
2 - Dehydration due to diuretic use
3 - Erythropoietin (EPO) producing tumour
4 - Chronic myeloid leukaemia
5 - COPD

Answer 15

5 - COPD

The patient in this example has risk factors for secondary polycythaemia including COPD and smoking. Impaired oxygen exchange in the lungs can result in a low PaO2 which results in stimulation of EPO release from the kidneys. EPO stimulates erythropoiesis and increases red cell mass, thereby resulting in polycythaemia. The low SpO2 is highly suggestive of a hypoxic driven polycythaemia. Therefore the most likely answer is COPD.