Classic Acquired Prothrombotic Conditions Although there is a growing number of known established thrombophilias with an underlying genetic basis, the majority of venous thromboembolism events are provoked in the context of an acquired hypercoagulability state, leading to venous thrombosis. These…
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…