Disadvantages of cPRP Aggregation Assays

Problems with these assays include (1) potential for false-positive interpretation if heparin produces nonspecific aggregation of donor platelets, an effect that could be enhanced nonspecifically by proaggregatory factors in the patient serum or plasma, and (2) risk of false-negative interpretation if HIT serum-induced platelet aggregation begins even before addition of heparin.

Nonspecific activation of platelets by heparin occurs with some normal donor c-PRP (Chong et al., 1993a), rendering these donors unsuitable for diagnostic testing. It is also possible that plasma from very sick patients may be more likely to cause nonspecific aggregation of platelets in c-PRP in the presence of heparin (Goodfellow et al., 1998).

An important practical disadvantage is that only a limited number of platelet aggregation tracings can be performed using conventional aggregometers. Thus, relatively few reactions with a limited number of patient and control samples can be evaluated.

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