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Sunday 5 July 2026

Peer Reviewed

Feature Article Haematology

A revised guide to the diagnosis of polycythaemia

John H Gallo

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Abstract

The diagnosis of polycythaemia has recently been improved by the discovery of a gene mutation that 95% of affected patients possess.

Key Points

Polycythaemia vera is a myeloproliferative disorder that needs to be distinguished from other causes of an elevated haemoglobin level. A reduction in the plasma volume (relative polycythaemia), an increase in erythropoietin secretion (secondary polycythaemia) and smoking (smoker’s polycythaemia) can all increase the haemoglobin level.
The diagnosis of polycythaemia vera has been simplified with the finding of a gene mutation present in 95% of patients with this condition.
If a patient’s haemoglobin level is borderline between normal and high, look for possible clinical causes such as dehydration or smoking. Remember that such findings may be normal in young men.
A high haemoglobin level is more important if intercurrent vascular disease is present because polycythaemia vera is a risk factor for both arterial and venous thrombosis.