Laboratory investigations and prediction of thrombotic risk in polycythemia vera

Thrombotic accidents remain a major cause of morbidity and of fatal outcome in polycythemia vera (PV). High haematocrit which increases whole blood viscosity is the only identified predictive factor of thrombosis in PV. Neither high platelet count nor any abnormal platelet function have been found significantly linked to the thrombotic risk. There are recent development allowing to better characterize plasma hypercoagulability. The predictive value of these new tests has not yet been evaluated in PV.