Polycythemia

Question 1

What is Polycythaemia?

Answer 1

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

Question 2

What are the 2 classifications of polycythaemia?

Answer 2

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

Question 3

Give the name and describe the aetiology of primary polycythaemia

Answer 3

Polycythaemia Rubra Vera
Clonal proliferation of myeloid cells with varied morphologic maturity + haematopoietic efficiency
Due to mutations in JAK2

Question 4

What are the 2 broad causes of secondary polycythaemia? Give examples of each

Answer 4

Appropriate increase in EPO: 
Due to chronic hypoxia (e.g. chronic lung disease, living at high altitude) which leads to upregulation of EPO.  
Inappropriate increase in EPO:
Renal (carcinoma, cysts, hydronephrosis)  
Hepatocellular carcinoma  
Fibroids  
Cerebellar haemangioblastoma  
EPO abuse by athletes

Question 5

Describe the epidemiology of polycythaemia

Answer 5

Annual UK incidence: 1.5/100,000

Peak age: 45-60 yrs

Question 6

List 4 symptoms of polycythaemia

Answer 6

Headaches
Pruritis after hot bath
Burning sensation in fingers + toes (erythromelalgia)
Thrombosis (DVT, stroke)

Question 7

List 7 signs of polycythaemia

Answer 7

Plethoric complexion (red, ruddy) 
Scratch marks from itching  
Conjunctival suffusion (redness)  
Retinal venous engorgement  
HTN
Hepatosplplenomegaly (in 75% of cases) 
Signs of underlying aetiology in secondary

Question 8

What bloods are required on FBC for diagnosis of polycythaemia?

Answer 8

High Hb
High haematocrit
Low MCV

Question 9

Which test distinguishes between relative polycythemia and absolute polycythaemia? How?

Answer 9

Isotope Dilution Techniques

Allows confirmation of plasma volume + red cell mass

Question 10

What investigations should be performed in secondary polycythaemia?

Answer 10

Exclude chronic lung disease/ hypoxia

Check for EPO-secreting tumours

Question 11

List causes of relative polycythaemia

Answer 11

May be acute: due to dehydration (e.g. diuretics, burns, enteropathy, alcohol)
Chronic form associated with obesity, HTN, high alcohol + tobacco intake
Gaisbock’s syndrome

Question 12

What blood results characterise Polycythaemia Rubra Vera?

Answer 12

High Hb, RCC, HCT, PCV
High WCC
High platelets
Low serum EPO

Question 13

Which genetic screen is used in diagnosing Polycythaemia Rubra Vera? Describe this

Answer 13

JAK2 mutation gene screen

Not specific alone for PV as is found in other haem disorders, but if mutation isnt present it makes PV much less likely

Question 14

What is seen on bone marrow trephine and biopsy in primary polycythaemia?

Answer 14

erythroid hyperplasia + raised megakaryocytes

Question 15

How does serum EPO differ in primary and secondary polycythemia?

Answer 15

Primary: Low EPO
Secondary: High EPO

Question 16

Who is affected by Gaisbock’s syndrome? What does this result in?

Answer 16

Occurs in young male smokers with HTN, which results in a decrease in plasma volume + an apparent increase in red cell count

Question 17

What class of disorders does polycythaemia vera fall into?

Answer 17

Myeloproiferative disorder