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Updated: Aug 23, 2026
A Uniform Shear Assay for Human Platelet and Cell Surface Receptors via Cone-plate Viscometry
Published on: June 5, 2019
[Platelet reactivity index by Grotemeyer]
J Koscielny1, O Meyer, H Kiesewetter
1Institut für Transfusionsmedizin, Charité, Universitätsmedizin Berlin, Campus Charité Mitte, Schumannstr. 20/21, 10117 Berlin. juergen.koscielny@charite.de
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 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.
Insights
The platelet reactivity index (PR) is a quick and affordable test to assess platelet aggregation, helping identify patients who may not respond to aspirin therapy for stroke and cardiac ischemia.
Area of Science:
- Hematology
- Biomedical Engineering
- Medical Diagnostics
Context:
- The determination of circulating platelet aggregates is crucial for understanding thrombotic events.
- Previous methods for assessing platelet aggregation have been refined over time.
- The Platelet Reactivity Index (PR) offers a streamlined approach to evaluating platelet function.
Purpose:
- To describe the Platelet Reactivity Index (PR) as a method for determining circulating platelet aggregates.
- To highlight the diagnostic utility of PR in identifying patients with abnormal platelet aggregation.
- To evaluate the effectiveness of PR in predicting response to antiplatelet therapy.
Summary:
- The PR method utilizes differential buffer solutions to measure platelet aggregates, with results automatically estimated.
- Elevated PR values (above 1.05 or 1.2) indicate increased platelet aggregation and potential pathological changes.
- The PR test is cost-effective and rapid, proving successful in identifying non-responders to aspirin therapy in stroke and cardiac ischemia patients.
Impact:
- PR values correlate significantly with arterial thromboembolic complications.
- The PR demonstrates strong correlation with other established platelet function tests like RT-H and PFA-100.
- PR serves as a predictive tool for evaluating aspirin therapy efficacy, although not for determining overdosage.
