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All About Bleeding

Fibrinogen (Factor I) Deficiencies

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Fibrinogen (also called factor I) is a protein synthesized in the liver that plays a critical role in the coagulation cascade (the clotting process). During the third phase of the coagulation cascade (the propagation phase), circulating fibrinogen is converted into fibrin.1 This forms insoluble strands creating a hemostatic plug to stem the flow of blood.2 When fibrinogen levels are well below normal, there is a risk of bleeding episodes of varying severity.1

Congenital & Acquired Fibrinogen Deficiency

Fibrinogen (factor I) deficiency can be congenital or acquired. It may take one of three different forms:3

  • A complete absence of fibrinogen (afibrinogenemia)
  • Very low, but detectable levels of fibrinogen (hypofibrinogenemia)
  • Near normal fibrinogen levels, but the protein is dysfunctional (dysfibrinogenemia)

Congenital (inherited) fibrinogen deficiency is rare and the prevalence is similar in males and females.4 It is classified as either type I (afibrinogenemia and hypofibrinogenemia) or type II (dysfibrinogenemia).

Acquired fibrinogen deficiencies account for most cases of fibrinogen-related severe bleeding. Excessive blood loss may exhaust the body’s supply of fibrinogen (consumption). Alternatively, the plasma concentration of fibrinogen may be reduced by dilution (e.g. during volume replacement therapy, when a drip or cell saver replaces lost blood volume but does not replace clotting factors). Acquired fibrinogen deficiency can also occur due to an underlying disease that limits fibrinogen synthesis (e.g. liver disease).5

CSL Behring Products

For more information about Factor I deficiency treatment options, please visit the following resources*:

Package Inserts

Product Websites

RiaSTAP.com (United States)

*Not all products are available in every country. To learn what products are available in your country, visit your CSL Behring country site.

Last Updated: 4/23/2015 4:22 PM
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