A new automated technique for platelet aggregation measurement

A Multistat III Centrifugal Analyser (MCA) was used to measure platelet aggregation in vitro. It has a capacity of about 40 samples per h. In the analyser platelet-rich plasma and collagen-reagent were mixed, and the turbidity was measured as a function of time. The results were presented in arbitrary units ( arb . units), i.e. change in turbidity per min X 1000. The estimated 0.95 reference range was 50-95 arb . units, (n = 46) and the coefficient of correlation between MCA results and results obtained by conventional aggregometry ( Fibromat ) was 0.85 (P less than 0.001). The MCA method registered 50-75% reduction of platelet aggregation after intake of low dose acetylsalicylic acid (ASA) (1.2-4.0 mg/kg) during 3 days in 19 subjects. The MCA method is suitable to monitor ASA treatment routinely in order to establish an individual appropriate ASA dose during prophylactic treatment of arterial thromboembolic disease.