Article

Thrombin generation assays: Accruing clinical relevance

Synapse BV, Cardiovascular Research Institute, 6200 MD Maastricht, The Netherlands.
Current Opinion in Hematology (Impact Factor: 3.97). 06/2004; 11(3):170-5. DOI: 10.1097/01.moh.0000130314.33410.d7
Source: PubMed

ABSTRACT

After decades of near oblivion, thrombin generation is being revived as an overall function test of the plasmatic coagulation system in platelet-poor plasma (PPP). In platelet-rich plasma (PRP) it assesses platelet procoagulant functions as well.
The recently developed use of special fluorogenic thrombin substrates allows monitoring of thrombin concentration in clotting PPP and PRP on line in up to 24 parallel samples. Studies in model systems stress the importance of cell-bound thrombin generation such as measured in PRP.
The method can be profitably applied to various hitherto unyielding problems such as the control of (low-molecular-weight) heparin therapy, the detection of lupus anticoagulant, and various forms of thrombomodulin and activated protein C resistance (including the use of oral contraceptives) as well as monitoring the treatment of hemophiliacs by factor VIII bypassing therapy. In PRP it reflects the abnormalities encountered in von Willebrand disease and Glanzmann and Bernard-Soulier thrombopathy as well as the action of antiplatelet drugs.

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Available from: H. Coenraad Hemker
    • "Reconstituted systems are as realistic as our insight into the clotting mechanism allows: extrapolation to physiology should therefore be regarded with due suspicion. Hemker et al. 58 (2004, p. 171). "
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    ABSTRACT: Traumatic-induced coagulopathy (TIC) is a hemostatic disorder that is associated with significant bleeding, transfusion requirements, morbidity and mortality. A disorder similar or analogous to TIC was reported around 70 years ago in patients with shock, hemorrhage, burns, cardiac arrest or undergoing major surgery, and the condition was referred to as a "severe bleeding tendency," "defibrination syndrome," "consumptive disorder," and later by surgeons treating US Vietnam combat casualties as a "diffuse oozing coagulopathy." In 1982, Moore's group termed it the "bloody vicious cycle," others "the lethal triad," and in 2003 Brohi and colleagues introduced "acute traumatic coagulopathy" (ATC). Since that time, early TIC has been cloaked in many names and acronyms, including a "fibrinolytic form of disseminated intravascular coagulopathy (DIC)." A global consensus on naming is urgently required to avoid confusion. In our view, TIC is a dynamic entity that evolves over time and no single hypothesis adequately explains the different manifestations of the coagulopathy. However, early TIC is not DIC because an increased thrombin-generating potential in vitro does not imply a clinically relevant thrombotic state in vivo as early TIC is characterized by excessive bleeding, not thrombosis. DIC with its diffuse anatomopathologic fibrin deposition appears to be a latter phase progression of TIC associated with unchecked inflammation and multiple organ dysfunction.
    No preview · Article · Aug 2015
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    • "Thrombin is generated at phosphatidylserine-exposing membranes from the damaged vessel wall and highly activated platelets [3]. Its formation and inactivation can precisely be measured in platelet-rich plasma or blood by thrombin generation assays [4]. Antithrombin in plasma binds and inactivates thrombin, a process that is enhanced by heparins. "
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    ABSTRACT: In this review, we presume that the process of thrombus formation, as assessed in whole blood flow studies and in experimental (murine) thrombosis studies, reflects the platelet responses in human hemostasis and thrombosis. Following this concept, we give an up-to-date overview of the main platelet receptors and signaling pathways that contribute to thrombus formation and are used as targets in (pre)clinical intervention studies to prevent cardiovascular disease. Discussed are receptors for thrombin, thromboxane, ADP, ATP, prostaglandins, von Willebrand factor, collagen, CLEC-2 ligand, fibrinogen and laminin. Sketched are the consequences of receptor deficiency or blockage for hemostasis and thrombosis in mouse and man. Recording of bleeding due to (congenital) platelet dysfunction or (acquired) antiplatelet treatment occurs according to different protocols, while similar laboratory methods are used to determine platelet function.
    Preview · Article · Nov 2013 · Blood reviews
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    • "Thrombin also activates platelets, and furthermore, besides procoagulant effects it has also anticoagulant effects following its binding to thrombomodulin. Ex vivo TG tests, like CAT, measure the haemostatic function of the blood, determined by simultaneous prothrombin activation and thrombin inactivation [9]: it measures the remaining capacity of blood to generate a thrombin burst indicating an increased risk of thrombosis or bleeding [11]. In contrast, in vivo TG, revealed by products like prothrombin fragment F1+2, thrombin antithrombin complex, and d-dimers, provides indications of TG that has already occurred [12] at the moment of blood collection. "
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    ABSTRACT: Background In this study the value of thrombin generation parameters measured by the Calibrated Automated Thrombography for prediction of blood loss after cardiac surgery with cardiopulmonary bypass was investigated. Methods Thirty male patients undergoing first-time coronary artery bypass grafting were enrolled. Blood samples were taken pre-bypass before heparinisation (T1) and 5 min after protamine administration (T2). Thrombin generation was measured both in platelet-rich plasma and in platelet-poor plasma. Besides thrombin generation measurements, activated clotting time, haematocrit, haemoglobin, platelet number, fibrinogen, antithrombin, D-dimers, prothrombin time and activated partial thromboplastin time were determined. Blood loss was measured and the amount of transfusion products was recorded postoperatively until 20 hours after surgery. Patients were divided into two groups based on the median volume of postoperative blood loss (group 1: patients with median blood loss <930 ml; group 2: patients with median blood loss ≥930 ml). Results On T1, patients of group 2 had a significantly lower endogenous thrombin potential and peak thrombin (p<0.001 and p=0.004 respectively) in platelet-rich plasma, a significantly lower endogenous thrombin potential (p=0.004) and peak thrombin (p=0.014) in platelet-poor plasma, and a lower platelet count (p=0.002). On T2 both endogenous thrombin potential and peak thrombin remain significantly lower (p=0.011 and p=0.010) in group 2, measured in platelet-rich plasma but not in platelet-poor plasma. In addition, platelet number remains lower in group 2 after protamine administration (p=0.002). Conclusions The key finding is that the Calibrated Automated Thrombography assay, performed preoperatively, provides information predictive for blood loss after cardiac surgery.
    Full-text · Article · Jun 2013 · Journal of Cardiothoracic Surgery
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