title: Use of the platelet reactivity index by Grotemeyer, platelet function analyzer, and retention test Homburg to monitor therapy with antiplatelet drugs.
abstract: 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 calculated. 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 euro dollars) and rapid to perform. PR values were used successfully to identify nonresponders to secondary prophylaxis with acetylsalicylic acid (ASA), that is, patients suffering from stroke (33%) and patients after cardiac ischemia (18%). Furthermore, elevated PR values correlated significantly with the incidence of arterial thromboembolic complications. The PR correlated well in our prospective study with values received from the retention test Homburg (RT-H) and the platelet function analyzer (PFA-100). The data indicate that the values of the PR seem to be highly predictive for the evaluation of the ASA therapy. However, the PR is not feasible for the determination of the ASA overdosage.
authors.affiliation: Institute for Transfusion Medicine, Charité Humboldt-University, Berlin, Germany. juergen.koscielny@charite.de
authors.forename: Jürgen
authors.initials: J
authors.lastname: Koscielny
authors.forename: Tunay
authors.initials: T
authors.lastname: Aslan
authors.forename: Oliver
authors.initials: O
authors.lastname: Meyer
authors.forename: Holger
authors.initials: H
authors.lastname: Kiesewetter
authors.forename: Friedrich
authors.initials: F
authors.lastname: Jung
authors.forename: Christof
authors.initials: C
authors.lastname: Mrowietz
authors.forename: Reinhard
authors.initials: R
authors.lastname: Latza
mesh_terms: D001241:Aspirin / Q000494:pharmacology; D001792:Blood Platelets / Q000187:drug effects*; D002986:Clinical Trials as Topic; D016903:Drug Monitoring / Q000379:methods*; D004492:Edetic Acid / Q000494:pharmacology; D005260:Female; D005434:Flow Cytometry; D005557:Formaldehyde / Q000494:pharmacology; D006801:Humans; D015539:Platelet Activation; D010973:Platelet Adhesiveness; D010974:Platelet Aggregation; D010975:Platelet Aggregation Inhibitors / Q000494:pharmacology*; D010976:Platelet Count; D010979:Platelet Function Tests / Q000191:economics / Q000295:instrumentation / Q000379:methods*; D011247:Pregnancy; D011446:Prospective Studies; D013923:Thromboembolism; D013997:Time Factors
chemical_list: D010975:Platelet Aggregation Inhibitors; D005557:Formaldehyde; D004492:Edetic Acid; D001241:Aspirin