Platelet function testing: quality assurance

Platelet function tests are widely used for the diagnosis of platelet disorders. In recent years there has been increasing interest in the use of platelet function tests to monitor antiplatelet drug therapy. Quality assurance is important to optimize the performance of laboratory assays but it has not been widely applied to platelet function tests. This deficiency likely reflects the need to use freshly collected blood samples for platelet function tests, and the complex, time-consuming nature of some assays such as aggregation studies. Platelet function testing lacks guidelines, is poorly standardized between laboratories, and rarely is evaluated by internal and external quality assurance exercises. The sensitivity, specificity, and diagnostic utility of some newer, simplified assays of platelet function have been evaluated in a range of clinical settings but corresponding quality assurance data for many established as well as emerging platelet function assays are lacking. Quality assurance issues relevant to testing platelet function are reviewed in this article, with a focus on their application to established and to new and emerging tests.