Haematology: Pathology - Polycythaemia

Question 1

Explain the difference between relative and absolute polycythaemia

Answer 1

Relative: increased RBC count due to haemoconcentration (e.g. in dehydration)
Absolute: increased total RBC mass

Question 2

What is the difference between primary and secondary absolute polycythaemia?

Answer 2

Primary: due to abnormalities of haematopoietic precursors
Secondary: in response to elevated EPO

Question 3

What is the most common cause of primary polycythaemia?

Answer 3

Polycythaemia vera

Question 4

Give four examples of high-EPO states which cause secondary polycythaemia

Answer 4

1. Lung disease
2. High-altitude living
3. Cyanotic heart disease
4. Paraneoplastic (RCC, HCC)