Drug-induced thrombocytosis.

Thrombocytosis is generally defined as platelet counts greater than 400,000/mm3. Thrombocytosis can be either primary or secondary. Adrenalin was one of the first drugs noticed to cause platelet elevations, probably due to demargination of platelets in the pulmonary vasculature. Vinca alkaloids have the most convincing data to show that they can induce thrombocytosis through their thrombocyte-stimulating properties. Miconazole has been implicated in causing thrombocytosis and has a documented case validated by drug rechallenge. Iron, predictably, can cause a transient thrombocytosis. The beta-lactam antibiotic data are very difficult to interpret due to the possibility of an acute-phase reaction in an infected patient being the cause of the thrombocytosis.