This site is intended for healthcare professionals
Last reviewed dd mmm yyyy. Last edited dd mmm yyyy
Polycythemia vera (PV) has been recognized as the main cause of primary erythrocytosis (1).
In polycythaemia rubra vera, as with all myeloproliferative disorders, there are excess granulocytic, and megakaryocytic elements, all derived from a single multipotent stem cell (neutrophilia in approximately two-thirds and thrombocytosis in 50% of PV cases can be seen) (1)
However, in polycythaemia vera the erythroid precursors dominate, and hence there is an absolute increase in red cell mass and blood volume. In polycythaemia rubra vera the erythroid offspring are unusual in being sensitive eg to insulin-like growth factor ± interlukin-3 - they are also do not require erythropoietin to avoid apoptosis (programmed cell death).
Polycythaemia rubra vera presents at an average age of 60 years (1). Annual incidence may vary widely between 0.2/100,000/year to a highest of 28/100,000/year (in Goteborg, Sweden) (1)
Haematocrit (Hct) values may be underestimated in iron deficient anaemia and may result in masking of polycythaemia vera (1).
Polycythaemia vera is a myeloproliferative neoplasm known to be associated with dysregulated signalling of the Janus associated kinases JAK1 and JAK2.
The identification of JAK2 mutations in almost all PV patients has revolutionised the diagnosis of PV. The JAK2 V617F mutation can be found in over 95% of PV patients (and an exon 12 mutation in most remaining patients)
Recommended diagnostic criteria for PV:
JAK2-positive polycythaemia vera (requires both criteria)
JAK2-negative polycythaemia vera (requires A1-A4 plus another A or two B criteria) *
*This is a very rare clinical entity
Pegylated interferon formulations have overall shown similar efficacy to hydroxyurea (3)
NICE stated that
Ruxolitinib is an orally available small-molecule tyrosine kinase inhibitor that is a potent and selective inhibitor of JAK1/JAK2