The diagnostic criteria of polycythaemia rubra vera.

There is no single diagnostic marker for polycythaemia vera (PV). The Polycythemia Vera Study Group established diagnostic criteria more than twenty years ago. Since some new laboratory and clinical investigations have developed, these criteria can now be updated. It is proposed that the overall pattern of major and minor criteria should remain. A raised red cell mass (greater than 25% above the patient's mean normal predicted value based on surface area) and absence of a cause of secondary polycythaemia are essential criteria. Then either palpable splenomegaly or the presence of a marker of clonal haemopoiesis would support the diagnosis of PV. In the absence of both of these latter major criteria, at least two minor criteria must be present to secure the diagnosis. These are: platelet count > 400 x 10(9)/l; neutrophil count > 10 x 10(9)/l; splenomegaly demonstrated by a scanning technique; characteristic BFU-E growth or reduced serum erythropoietin value.