Polycythaemia

Question 1

Define polycythaemia? and what are the 2 classifications of polycythaemia?

Answer 1

An increase in haemoglobinconcentration above the upper limit of normal for a person’s age and sex. Classified into:

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

Question 2

what are the primary causes of polycythaemia?

Answer 2

Polycythaemia Rubra Vera – primary cause

• Characterised by clonal proliferation of myeloid cells
• They have varied morphologic maturity and haematopoietic efficiency
• Mutations in JAK2 tyrosine kinase are involved

Question 3

what mutation is associated with primary polycythaemia?

Answer 3

Mutations in JAK2 tyrosine kinase

Question 4

what are the causes of secondary polycythaemia?

Answer 4

increase in EPO

Appropriate increase in erythropoietin

• Due to chronic hypoxia(e.g. chronic lung disease, living at high altitude)
• This leads to upregulation of erythropoiesis

Inappropriate increase in erythropoietin

• Renal (carcinoma, cysts, hydronephrosis)
• Hepatocellular carcinoma
• Fibroids
• Cerebellar haemangioblastoma
• Secondary polycythaemia may be due to erythropoietin abuse by athletes

Question 5

whata are the causes of relative polycythaemia?

Answer 5

May be acute – due to dehydration (e.g. diuretics, burns, enteropathy, alcohol)

Chronic form associated with obesity, hypertension, high alcohol and tobacco intake

Gaisbock’s syndrome

• Occurs in young male smokers with hypertension, which results in a decrease in plasma volume and an apparent increase in red cell count

Question 6

what is Gaisbock’s syndrome?

Answer 6

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

Question 7

summarise the epidemiology of polycythaemia?

Answer 7

Annual UK incidence: 1.5/100,000

Peak age: 45-60 yrs

Question 8

what are the presenting symptoms of polycythaemia?

Answer 8

Due to hyperviscocity

headaches

pruiritis

burning sensation in fingers and toes ( erythromelagia)

Thrombosis ( DVT and stroke)

Question 9

what are the signs of polycythaemia on physical examination?

Answer 9

plethoric complexion ( red, ruddy)

Hepatosplplenomegaly (in 75% of cases)
scratch marks from itching

conjuctival suffision (redness of conjuctiva)

retinal venous engorgement

hypertension

Question 10

describe the investigations and results for pollycythaemia rubra vera and interpret the results?

Answer 10

High Hb, High haematocrit, low MCV

High WCC

High platelets

Low serum EPO

JAK2 mutation gene screen – not specific alone for PV as it is found in other haem disorders, but if mutation isnt present it makes PV much less likely

Bone marrow trephine and biopsy shows erythroid hyperplasia and raised megakaryocytes

Question 11

what is seen on the trephine and biopsy in polycythaemia rubra vera?

Answer 11

erythroid hyperplasia and riased megakaryocytes

Question 12

describe the FBC in polycythaemia?

Answer 12

High Hb

High haematocrit

Low MCV

High platelets

High WBC

Question 13

How are the investigations results different for secondary polycythaemia?

Answer 13

High serum EPO

Exclude chronic lung disease/hypoxia

Check for EPO-secreting tumours