Clinics in laboratory medicine
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Thromboelastography (TEG) as a method of assessing global hemostatic and fibrinolytic function has existed for more than 60 years. Improvements in TEG technology have led to increased reliability and thus increased usage. The TEG has been used primarily in the settings of liver transplant and cardiac surgery, with proven utility for monitoring hemostatic and fibrinolytic derangements. ⋯ Disadvantages of TEG include a relatively high coefficient of variation, poorly standardized methodologies, and limitations on specimen stability of native whole blood samples. In the pediatric setting, an additional advantage of the TEG is a relatively small sample volume, but a disadvantage is the difference in normal ranges between infants, especially newborns, and adults. In summary, TEG is an old concept with new applications that may provide a unique perspective on global hemostasis in various clinical settings.
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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.
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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.