Heparin-associated thrombocytopenia in a patient with polycythemia vera: the importance of a marked drop in platelet count.

The present report describes a patient with polycythemia vera who developed a severe arterial and venous thrombosis caused by systemically administered heparin. An immunologic implication has been proposed as pathophysiological mechanism of this heparin-associated thrombocytopenia and thrombosis syndrome. It is suggested, however, that a strong decrease in platelet count as occurred in this patient leads to a higher chance of developing this complication.