Clinics in laboratory medicine
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Ebola and Marburg viruses cause a severe viral hemorrhagic fever disease mainly in Sub-Saharan Africa. Although outbreaks are sporadic, there is the potential for filoviruses to spread to other continents unintentionally because of air travel or intentionally because of bioterrorism. This article discusses the natural history, epidemiology, and clinical presentation of patients infected with Ebola and Marburg viruses. Clinicians in the United States should be aware of the symptoms of these viral infections in humans and know the appropriate procedures for contacting local, state, and national reference laboratories in the event of a suspected case of filoviral hemorrhagic fever.
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Turnaround time for molecular diagnostic tests is critical in detecting infectious agents, in determining a patient's ability to metabolize a drug or drug class, and in detecting minimal residual disease. These applications would benefit from the development of a point-of-care device for nucleic acid extraction, amplification, and detection. ⋯ The creation of such a device requires miniaturization of current technologies and the use of microfluidics, microarrays, and small-diameter capillary tubes to reduce reagent volumes and simplify heat conduction by convection during nucleic acid amplification. This ideal device may be available in 3 to 5 years and will revolutionize and expand the global availability of molecular diagnostic assays.
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Point-of-care (POC) assays are available for a variety of coagulation tests. These assays are generally simple to perform and have a more rapid turnaround time than their central-laboratory counterparts. This article discusses the current status of coagulation POC methodologies, focusing on the potential clinical uses and the limitations of platelet function testing, prothrombin time/international normalized ratio, D-dimer, and activated clotting time (ACT). Additional studies are eagerly awaited regarding potential future uses of POC coagulation testing, including the role of platelet function testing and ACT heparin management systems.
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Much has been learned about thrombotic thrombocytopenic purpura (TTP) and heparin-induced thrombocytopenia (HIT) and much remains a diagnostic and management challenge. While the pentad of thrombocytopenia, microangiopathic hemolytic anemia, fever, and renal and neurologic abnormalities characterize the clinical presentation of TTP, few patients present with all signs and symptoms. ⋯ HIT is another systemic disorder presenting with thrombocytopenia and/or thrombosis with potential devastating consequences whose diagnosis is difficult and management is still evolving. Highlights of the conditions and clinical and laboratory hints that allow physicians to diagnose TTP and HIT efficiently and offer patients the best available therapeutic interventions are presented.
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This article reviews the variety of coagulation testing abnormalities identified and the evidence demonstrating their lack of correlation with hemostasis and inability to predict bleeding for patients with liver disease. The article discusses the historical and incorrect evolution of the commonly used "1.5x" prothrombin time/international normalized ratio "threshold" for fresh frozen plasma/frozen plasma (FFP/FP) administration. Finally, this article reviews why FFP/FP cannot correct minimally prolonged clotting times in patients with liver disease, nor provide adequate prophylaxis against bleeding from percutaneous liver biopsy.