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INTRODUCTION

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  • Inherited deficiencies of coagulation factors other than factor VIII (hemophilia A) and factor IX (hemophilia B) are rare bleeding disorders that occur in most populations.

  • Patients are usually homozygotes or compound heterozygotes.

  • Factor XI and factor VII deficiency occur relatively frequently, and other deficiencies are relatively rare (Table 81–1).

  • The severity of the bleeding disorder usually relates to the severity of the factor deficiency.

  • All may be caused by decreased synthesis of a specific coagulation factor, by synthesis of a dysfunctional form of the coagulation factor, or both.

  • Inherited deficiency of a coagulation factor does not protect patients from thrombosis.

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Table Graphic Jump Location
TABLE 81–1RELATIVE PREVALENCE OF RARE BLEEDING DISORDERS*
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PROTHROMBIN (FACTOR II) DEFICIENCY

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Pathogenesis

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  • Hypoprothrombinemia or dysprothrombinemia may be involved.

  • Both are inherited as autosomal recessive disorders.

  • Both interfere with hemostasis by impairing thrombin generation.

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Clinical Features

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  • The disorders are characterized by mucocutaneous and soft-tissue bleeding, usually in proportion to the severity of the functional prothrombin deficiency.

  • Bleeding may be spontaneous if prothrombin levels are less than 1%. Hemarthroses may occur.

  • Individuals with higher prothrombin levels have a variable bleeding tendency, and some may be asymptomatic.

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Laboratory Features

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  • The activated partial thromboplastin time (aPTT) and prothrombin time (PT) are prolonged. The thrombin time (TT) is normal.

  • Diagnosis is established by demonstrating reduced levels of functional prothrombin.

  • Both functional and antigen assays are required to identify dysprothrombinemia. Immunoelectrophoretic studies may demonstrate some forms of dysprothrombinemia.

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Differential Diagnosis

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  • Differential diagnosis includes inherited factor V or factor X deficiency, acquired deficiency of the vitamin K–dependent factors, or lupus anticoagulant.

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Treatment

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  • Prothrombin deficiency may be corrected with intravenous prothrombin complex concentrates, but with risk of transmission of viruses not ...

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