Polycythaemia / Myeloproliferative Neoplasm Workup

Polycythaemia: Hb >185 g/L (M) / >165 g/L (F) OR haematocrit >0.52 (M) / >0.48 (F). Confirm true erythrocytosis (not pseudopolycythaemia from dehydration / smoking). • Distinguish primary (PV) vs secondary (hypoxia, EPO-secreting tumour, COPD, OSA, smoking, high altitude, congenital). Thrombocytosis: platelets >450 × 10⁹/L. Distinguish reactive (infection, inflammation, IDA, malignancy, splenectomy) from primary (ET, PV, CML, MF). MPN suspicion: pruritus (especially aquagenic), erythromelalgia, splenomegaly, headache, paraesthesia, thrombosis (often unusual sites — splanchnic, cerebral, hepatic vein), gout (urate ↑).