EFFECT OF DIFFERENT SAMPLE PREPARATION METHODS ON THE RESULTS OF THE IMPEDANCE TECHNIQUE IN THE STUDY OF PLATELET HYPER-FUNCTION AND HYPO-FUNCTION IN WHOLE-BLOOD

In 1980 Cardinal and Flower (1) introduced the electronic aggregometer that measures platelet aggregation registering the increase in impeda nce across two platinum electrodes placed in the sample and allows inv estigation of platelet aggregation in whole blood (WB). A major proble m with this method is the lack of standardization. In fact, some autho rs measure platelet aggregation in undiluted samples, while others stu dy platelet function after dilution of WB with physiological solution or platelet poor plasma (PPP). These differences in methodology may be responsible for different results, since several studies demonstrated that platelet and erythrocyte concentration of the sample influences platelet aggregation. In the case of platelet count, significantly pos itive relationship (increased aggregation with increased platelet coun ts) was observed (1-3), while inverse correlation occurred between hem atocrit and aggregation (increased aggregation with lower hematocrit v alues) (2,4,5). Moreover, it has been suggested that composition of th e suspending medium may influence both function of platelets and repro ducibility of the method (6). The present investigation was aimed at s tudying the effect of different sample preparation methods on the resu lts of platelet aggregation in WB.