Qualitative platelet defect in a case of heparin-induced thrombocytopenia

A qualitative platelet defect was demonstrated in a patient with heparin-induced thrombocytopenia. His platelets showed impaired aggregation to collagen and arachidonate and absent second wave aggregation to adenosine diphosphate and epinephrine but normal response to ristocetin. These aggregation abnormalities were similar to those reported in idiopathic thrombocytopenia and systemic lupus erythematosus. This platelet function defect may contribute to haemorrhagic complications which appear to be common in heparin-induced thrombocytopenia.