True polycythaemia needs to be distinguished from other causes of an elevated haemoglobin concentration. What tests are useful in the diagnosis and initial assessment?
- True polycythaemia 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.
- 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 males.
- 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.