What are nonplatelet hemostatic disorders?

Updated: Oct 06, 2020
  • Author: Irene S Pakos, DO; Chief Editor: Perumal Thiagarajan, MD  more...
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Blood coagulation is triggered by the exposure of tissue factor at injury sites, leading to the generation of minute quantities of thrombin. Thrombin, in turn, activates platelets, as well as factors XI, VIII, and V, and triggers the sequential activation of factors XI, IX, X, and prothrombin on the activated platelet surface, leading to the generation of sufficient thrombin to convert fibrinogen to fibrin and affect hemostasis. Platelets localize coagulation to the hemostatic thrombus and protect coagulation enzymes from inhibition by plasma and platelet inhibitors, thus preventing disseminated intravascular coagulation (DIC).

Abnormalities in the coagulation cascade that are independent of the platelet protective mechanisms can affect hemostasis. These abnormalities may be inherited or acquired.

Disorders of nonplatelet hemostasis can be divided into 2 groups based on whether they increase or decrease coagulation. The former may lead to thrombosis, the latter to hemorrhage. Such a division is not absolute, since some disorders may have both hemorrhagic and thrombotic manifestations.

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