Haematology & OncologyPending review

Polycythaemia Vera

A clonal myeloproliferative disorder, usually driven by a JAK2 mutation that makes marrow precursors hypersensitive to growth signals, so red cells (and often white cells and platelets) are overproduced independent of erythropoietin, raising blood viscosity and thrombosis risk while erythropoietin itself is suppressed.

In a nutshell

A JAK2 mutation makes marrow precursors proliferate independent of erythropoietin, expanding red cell mass and thickening the blood. Erythropoietin is suppressed as a result, which is the key test distinguishing this primary process from secondary polycythaemia.

Classic presentation

An incidental finding of a raised haematocrit on routine bloods, or a patient with facial plethora, headache and itching after a hot bath, found to have a raised haemoglobin.

Key points

JAK2 V617F constitutively activates the erythropoietin receptor pathway, making red cell production independent of erythropoietin.

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Educational content pending clinical review. Not medical advice.