[Platelet reactivity index by Grotemeyer].
In 1974 Wu and Hoak described a method for determining circulating platelet aggregates. This method was modified by Grotemeyer in 1983. The platelet reactivity index (PR) is based on the ratio of platelet aggregates in blood samples obtained in different buffer solutions. Platelet aggregates are resolved, when blood is sampled in EDTA-buffer, but remain fixed when EDTA-formalin-buffer is used. Generally, the PR is preferred, because in vitro manipulations of platelets are not necessary, and the results are estimated automatically. PR values above 1.05 are suspicious for elevated platelet aggregation. PR values above 1.2 indicate pathological changes in platelet aggregation. The PR is inexpensive (4.0 D ) and rapid to perform. PR-values were used successfully to identify non-responders to secondary prophylaxis with acetylsalicylic acid (ASA), i. e. patients suffering from stroke (33%) and after cardiac ischaemia (18%). Furthermore, elevated PR-values correlated significantly with the incidence of arterial thromboembolic complications. The PR correlated well in a own prospective study (drug monitoring) with values received from the retention test Homburg (RT-H) and the platelet function analyser (PFA-100). These data indicate that the values of the PR seems to be highly predictive for the evaluation of the ASA therapy. However, the PR is not suitable for the determination of ASA overdosage.
Institut für Transfusionsmedizin, Charité, Universitätsmedizin Berlin, Campus Charité Mitte, Schumannstr. 20/21, 10117 Berlin. juergen.koscielny@charite.de
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Koscielny
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Meyer
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Kiesewetter
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Jung
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Latza
D001792:Blood Platelets / Q000502:physiology; D002986:Clinical Trials as Topic; D006801:Humans; D015539:Platelet Activation / Q000502:physiology; D010979:Platelet Function Tests / Q000379:methods*; D015203:Reproducibility of Results