[Thrombocytosis: adverse effect of heparin treatment]. / La thrombocytose: un effet secondaire méconnu de l'héparinothérapie.

ABSTRACT

INTRODUCTION: Thrombocytosis induced by heparin is rarely reported in the literature. CASE We report here four cases of thrombocytosis, three in patients under treatment for a stable myeloproliferative disorder. Thrombocytosis always regressed when heparin treatment was discontinued, and no thrombotic events occurred. DISCUSSION: Following several reports suggesting an association between heparin and thrombocytosis, the French adverse drug reporting (pharmacovigilance) network identified 51 cases. Thrombocytosis associated with heparin is probably explained by the latter's potentiation of megakaryocytopoiesis, in particular, by inhibition of platelet factor 4 (PF4). Thrombocytosis is a further reason to monitor platelet counts during heparin treatment.