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 NICE CKS.
• 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 NICE CKS,NICE CKS.
• 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 NICE CKS,NICE CKS.
• Clinical features such as splenomegaly, elevated platelet and white blood cell counts, and a family history of myeloproliferative neoplasms increase suspicion and support diagnosis NICE CKS,NICE CKS.
• Referral to haematology is recommended urgently if PV is suspected or if symptoms of hyperviscosity are present, to confirm diagnosis and initiate treatment NICE CKS,NICE CKS.

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 NICE CKS,NICE CKS.

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 NICE CKS Tefferi & Vardiman 2008Langabeer et al. 2015.