What are the key diagnostic criteria for confirming a diagnosis of Polycythaemia Vera in primary care?

Key diagnostic criteria for confirming Polycythaemia Vera (PV) in primary care include:

• Initial identification of elevated haemoglobin or haematocrit levels indicating erythrocytosis, after excluding secondary causes such as smoking, hypoxia, or performance-enhancing drugs. Repeat blood sampling after addressing reversible causes (e.g., smoking cessation, oxygen therapy) is essential to confirm persistent erythrocytosis ¹.
• Testing for the JAK2 V617F mutation is a critical molecular diagnostic step, as its presence strongly supports a diagnosis of PV. If negative, further testing for less common JAK2 exon 12 mutations is indicated to definitively confirm or exclude PV ¹,².
• Assessment of serum erythropoietin (EPO) levels is important; low or suppressed EPO levels support PV diagnosis, whereas elevated EPO suggests secondary erythrocytosis and warrants referral for further evaluation ¹,².
• Clinical features such as splenomegaly, elevated platelet and white blood cell counts, and a family history of myeloproliferative neoplasms increase suspicion and support diagnosis ¹,².
• Referral to haematology is recommended urgently if PV is suspected or if symptoms of hyperviscosity are present, to confirm diagnosis and initiate treatment ¹,².

Additional considerations: Primary care should manage cardiovascular risk factors and monitor haematocrit levels if secondary causes are excluded and PV is confirmed. Annual follow-up is advised to detect disease progression or transformation ¹,².

This diagnostic approach aligns with the World Health Organization criteria emphasizing JAK2 mutation testing and exclusion of secondary causes, as well as the British Society for Haematology guidelines ¹ (Tefferi and Vardiman, 2008; Langabeer et al., 2015).