International journal of laboratory hematology
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Although the function of platelets in the maintenance of hemostasis has been studied in great detail, more recent evidence has highlighted a central role for platelets in the host inflammatory and immune responses. Platelets by virtue of their large numbers and their ability to rapidly release a broad spectrum of immunomodulatory cytokines, chemokines, and other mediators act as circulating sentinels. Upon detection of a pathogen, platelets quickly activate and begin to drive the ensuing inflammatory response. ⋯ Platelet-neutrophil interactions are known to induce the release of neutrophil extracellular traps (NETs) in response to either bacterial or viral infection, and platelets have been shown to internalize pathogens, sequestering them in engulfment vacuoles. Finally, emerging data indicate that platelets also participate in the host immune response by directly killing infected cells. This review will highlight the central role platelets play in the initiation and modulation of the host inflammatory and immune responses.
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Emergency hemostasis testing is typically used to determine which blood products are needed to correct hemostatic defects associated with bleeding. Rapid assessment of hemostasis can be performed using standard or viscoelastic hemostasis tests in the clinical laboratory, satellite laboratory, or using point-of-care methods. The major drawback of standard coagulation testing is that most clinical laboratories are focused more on accuracy than on turnaround time. ⋯ Viscoelastic testing is currently the only method that can detect severe fibrinolysis. Platelet function testing is useful for detection of hereditary platelet function problems and some antiplatelet medication monitoring, but is less useful for preoperative bleeding risk assessment or diagnosing the cause of acquire bleeding syndromes. This review will highlight different approaches to the rapid assessment of hemostasis.
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The introduction of several oral direct anticoagulants within the past 2-3 years has dramatically changed clinical practice and has also impacted on utilization and interpretation of coagulation laboratory testing. This article reviews the effects of the oral thrombin inhibitor, dabigatran, and the oral factor Xa inhibitors, rivaroxaban and apixaban, on screening and diagnostic coagulation tests, and describes methods for measuring the their anticoagulant activity in plasma. Currently, there are evidence gaps regarding the role of laboratory testing for surveillance and management of adverse events associated with these new anticoagulants which do not require routine therapeutic drug monitoring. This is a rapidly changing field, and coagulation laboratory experts have a major role in ensuring patients receive appropriate testing and accurate interpretations of results.