Heterogeneity of heparin lots associated with thrombocytopenia and thromboembolism.

Overview

Thromboembolic complications may develop in patients with heparin-associated thrombocytopenia, presumably due to the formation of platelet aggregates. An unexpectedly high incidence of pulmonary embolism following coronary artery bypass surgery occurred during a brief period of time at a single institution, and all of these cases were found to be associated with thrombocytopenia. All patients tested during thrombocytopenia (five of five) had an increase in platelet-associated antibody. Serum samples from all five patients tested caused normal platelets to aggregate in vitro in the presence of one specific lot of beef lung heparin, which was in use in the operating room at the time; none of six other lots of beef lung heparin mediated in vitro platelet aggregation. Heparinase digestion of the heparin abolished the aggregating activity. It is concluded that thrombocytopenia and platelet activation caused by heparin may vary greatly even among different lots of heparin prepared from the same source.