Clinical Performance Evaluation of T-TAS®01 HD Chip

This study will measure the improvement in thrombogenicity following platelet transfusion in patients with thrombocytopenia, using the T-TAS 01 HD assay, with a comparison with clinical truth, defined as the confirmation of increased platelet count attributed to platelet transfusion. The study will be conducted at a minimum of 3 locations in the United States and will enroll up to 90 subjects with thrombocytopenia and 50 healthy control subjects. The following subject populations will be enrolled into the study (enrollment numbers indicated in parentheses): * Ostensibly healthy subjects with a normal platelet count and without a history of hemostasis abnormalities, for establishing expected values for quality control (N = up to 50) * Subjects with thrombocytopenia who are planned to receive a platelet transfusion who have pre-transfusion and post-transfusion blood samples collected for testing (N = 50; up to 90 will be enrolled in the event that some subjects do not receive platelet transfusions after enrollment) Subjects will be recruited prospectively, and informed consent will be obtained after confirmation that the enrollment criteria described in Section 5a are satisfied. Blood samples will be collected after enrollment, and subject participation will be complete after all blood samples are collected and all necessary information is collected to complete the case report form (CRF). Blood sample testing with the T-TAS 01 and thromboelastography (TEG) assays will occur locally at each investigational site. Other required laboratory measurements (i.e. CBC) will be performed either locally or remotely, depending on the local availability.