title: Evaluation of ristocetin-Willebrand factor assay and ristocetin-induced platelet aggregation.
abstract: Normal subjects, patients with various bleeding disorders, and patients with von Willebrand's disease were studied. All patients with von Willebrand's disease had decreased levels of ristocetin-Willebrand factor (range, 0 to 41%) as compared with all other subjects (range, 79 to 202%). Ristocetin-induced platelet aggregation of platelet-rich plasma was abnormal in all patients with von Willebrand's disease tested, and it was possible to correct this abnormal response by addition of normal platelet-poor plasma. Abnormal ristocetin-induced platelet aggregation was seen in patients with intrinsic platelet disorders or, on some occasions, in normal patients who had ingested aspirin. Ristocetin-induced platelet aggregation is not diagnostic, but it may be useful as a simple screening test for patients with possible von Willebrand's disease. In conjunction with other tests, the assay for ristocetin-Willebrand factor will be useful in diagnosis and evaluation of these patients.
mesh_terms: D000925:Anticoagulants / Q000494:pharmacology; D000941:Antigens; D001778:Blood Coagulation Disorders / Q000097:blood; D001779:Blood Coagulation Factors / Q000032:analysis*; D001792:Blood Platelets; D005169:Factor VIII / Q000276:immunology / Q000378:metabolism; D006801:Humans; D010973:Platelet Adhesiveness / Q000187:drug effects*; D010974:Platelet Aggregation / Q000187:drug effects*; D012310:Ristocetin; D014842:von Willebrand Diseases / Q000097:blood*
chemical_list: D000925:Anticoagulants; D000941:Antigens; D001779:Blood Coagulation Factors; D012310:Ristocetin; D005169:Factor VIII