Chronic elevation of some coagulation factor levels is associated with an increased risk of venous thrombosis (factors VIII, IX, XI, II). Some of these show level dependence; the risk increases linearly with the plasma factor level (factors VIII, IX, II).…
Factor V Leiden Factor V Leiden (FVL) refers to the specific G-to-A transition at nucleotide 1601 (c.1601G>A) in exon 10 of the factor V gene, which results in arginine to glutamine substitution at amino acid 534 of the protein (p.Arg534Gln),…
Activated protein C (APC) resistance has a reported prevalence of 10%–15% and is a common cause of thrombophilia. The majority of APC resistance is directly attributable to heritable mutations in coagulation factor V (FV), primarily the FV Leiden (FVL) R506Q…
Protein S (PS) is a vitamin K–dependent plasma glycoprotein that serves as a cofactor of activated protein C (APC). When bound to APC, it accelerates protein C–dependent degradation of factor (F) Va and FVIIIa. PS deficiency is inherited in an…
Protein C (PC) is a vitamin K–dependent, heterodimeric, plasma glycoprotein that is synthesized as a zymogen in the liver. It is activated on the endothelial surface by the thrombin–thrombomodulin (TM) complex. Once produced, the activated protein C (APC) cleaves and…
Congenital antithrombin (AT) deficiency occurs in 0.2%–0.02% of the general population. However, in patients who had suffered a venous thromboembolic event (VTE), the prevalence is approximately 1%–3%. Preanalytical variables must be taken into account when deciding on the timing of…
Introduction Thrombophilia refers to the propensity to develop thrombosis and can be a result of acquired and/or inherited conditions. Inherited conditions are usually identified by a blood test, where acquired conditions are characterized by a patient’s clinical state or associated…
Abnormal thrombosis is a result of a pathologic shift in the balance between antihemorrhagic (prothrombotic) and antithrombotic factors toward conditions that favor thrombus formation at the wrong time and/or in the wrong location. The Virchow triad of blood stasis, inflammation,…
The purpose of this chapter is to provide an overview of laboratory techniques involved in fibrinolysis testing. Chapter 145 provides a general introduction to fibrinolytic testing and common fibrinolytic disorders ( Fig. 146.1 ). Open full size image Figure 146.1…
Physiology In healthy subjects, there is a dynamic equilibrium between coagulation and platelets forming a hemostatic plug to close the wound and the fibrinolytic system removing fibrin to prevent vascular occlusion. Fibrinolysis is initiated by the formation of fibrin. Tissue…