Chapter 3: Clotting Disorders

Original authors: Edith A. Nutescu, Jessica B. Michaud, Joseph A. Caprini, Louis W. Biegler, and Robert R. McCormick

Abstracted by Kellie R. Brown


  • Introduction
  • What is a D-Dimer Level?
  • Clotting Disorders
  • Hereditary Clotting Disorders
  • Group 1: A lack of anti-clotting factors in the blood
    • Antithrombin Deficiency
    • Protein C Deficiency
    • Protein S Deficiency
  • Group 2:  An increased amount of pro-clotting factors in the blood
    • Activated Protein C Resistance/Factor V LeidenMutation
    • Prothrombin Defects; Prothrombin Gene 20210A Mutation
    • Factor Elevations: Elevations in the levels of different proteins in the blood that participate in the clotting process
    • Hyperhomocysteinemia
  • Other Inherited Clotting Disorders
    • AntiPhospholipidantibody Syndrome (APS)
    • How common is it?
    • How and when do you test for this?
    • What is the risk of VTE in people with APS?
    • How do you treat APS?
  • Heparin Induced Thrombocytopenia
    • Heparin induced thrombocytopenia (HIT)
    • How common is HIT?
    • How and when do you test for HIT?
    • What is the risk of VTE in a person with HIT?
    • How do you treat HIT?
  • Cancer
  • Conclusion


The normal balance between clot formation and breakdown can be changed by the presence of certain genetic or acquired defects leading to abnormal clot formation.  In this chapter you will learn about different factors that can increase the risk of VTE.  These conditions should be looked for in any person who has a VTE, unless the cause is already known.      

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