A Prospective Study in 52 Patients

In a group of 52 patients receiving continuous intravenous heparin, 16 developed thrombocytopenia (platelets < 100 000/mm3). Ten of the 16 patients who had thrombocytopenia had elevated titers of fibrinogen-fibrin degradation products, and five of these 10 patients also had a reduction in plasma fibrinogen. The abnormalities disappeared after the heparin preparation was discontinued. These occurrences could not be attributed to drugs other than heparin, to the dose of heparin administered, or to prior exposure to heparin. The mechanism by which the heparin preparation may induce these changes is not known. THROMBOCYTOPENIA associated with the administration of heparin was first recognized in animals (1, 2) and was later observed in man (3). Several other anecdotal clinical reports have appeared (4-8). Suggested mechanisms have included in-vivo platelet aggregation, induction of platelet sequestration in the body, immune-mediated platelet de-struction, and disseminated intravascular coagulation. The incidence of thrombocytopenia in patients receiving heparin is unknown. Recently, we reported two cases in which disseminated intravascular coagulation with severe thrombocytopenia occurred during administration of hepa-rin (beef lung) for pulmonary emboli (7). Subsequently, the same phenomenon was observed in two other patients with venous thrombosis; data from these will be presented. This experience prompted a prospective study of the fre-quency of thrombocytopenia and disseminated intravascu-lar coagulation in patients receiving heparin. Two patients were observed before the prospective study was started, and they are not included in the data analysis