Understanding and evaluating platelet function.

The contribution of platelets to normal hemostasis and vascular disease is well described. However, recent studies make it clear that much remains to be learned about platelet activation at the single cell and the molecular level, and about the contribution of platelets to inflammation, tumor angiogenesis, and embryonic development. This article is divided into two themes. The first is an overview of current knowledge of the mechanisms that drive platelet function in vivo and a brief summary of some of the emerging ideas that are modifying older views. The second theme is a consideration of the strengths and weaknesses of the tools we have as hematologists to assess platelet function in the clinical setting, identify mechanisms, and evaluate the impact of antiplatelet agents.