Use of native or platelet count adjusted platelet rich plasma for platelet aggregation measurements.
BACKGROUND
It is still not clear whether native or platelet count adjusted platelet rich plasma (PRP) should be used for platelet aggregation measurements.


OBJECTIVE
To evaluate the necessity of using adjusted PRP in platelet function testing.


METHODS
Platelet aggregation with native PRP and adjusted PRP (platelet count: 250/nl, obtained by diluting native PRP with platelet poor plasma) was performed on the Behring Coagulation Timer (BCT(R)) using ADP, collagen, and arachidonic acid as agonists. Healthy subjects, patients on antiplatelet treatment, and patients with thrombocytosis (platelet counts in PRP > 1250/nl) were investigated.


RESULTS
No significant differences in the maximum aggregation response were seen when using either native or adjusted PRP from healthy subjects and patients on antiplatelet treatment. Nevertheless, some patients taking aspirin or clopidogrel showed reduced inhibition of ADP and arachidonic acid induced aggregation in adjusted PRP but not in native PRP. The maximum velocity of healthy subjects and patients on antiplatelet treatment varied significantly as a result of the degree of dilution of the adjusted PRP. Surprisingly, the BCT provided good results when measuring platelet aggregation of native PRP from patients with thrombocytosis, whereas commonly used aggregometers could not analyse platelet aggregation of native PRP in these patients.


CONCLUSIONS
The time consuming process of PRP adjustment may not be necessary for platelet aggregation measurements. Moreover, using adjusted PRP for monitoring aspirin or clopidogrel treatment may falsify results. Therefore, it may be better to use native PRP for platelet aggregation measurements, even in patients with thrombocytosis.
Department of Internal Medicine, Division of Vascular Medicine, University Hospital Theodor-Stern-Kai 7, Hs.13a EG, 60590 Frankfurt/Main, Germany. helenmani@gmx.de
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Mani
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Luxembourg
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Kläffling
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Erbe
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Lindhoff-Last
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001241:Aspirin / Q000494:pharmacology; D000077144:Clopidogrel; D016903:Drug Monitoring / Q000379:methods; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010974:Platelet Aggregation / Q000187:drug effects; D010975:Platelet Aggregation Inhibitors / Q000494:pharmacology; D010976:Platelet Count; D010979:Platelet Function Tests / Q000379:methods*; D013922:Thrombocytosis / Q000097:blood; D013988:Ticlopidine / Q000031:analogs & derivatives / Q000494:pharmacology
D010975:Platelet Aggregation Inhibitors; D000077144:Clopidogrel; D013988:Ticlopidine; D001241:Aspirin