factor XI (redirected from Coagulation factor XIa)

factor XI

n.

A factor in the clotting of blood, a deficiency of which results in a hemorrhagic tendency. Also called plasma thromboplastin antecedent.

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factor XI Plasma thromboplastin antecedent, PTA Hematology A 140–160 kD vitamin K-dependent serine proteinase of the intrinsic pathway of coagulation encoded on chromosome 4q35, which is activated in vitro by contact with a thrombogenic surface–eg, glass or thrombin and activates factor IX–IXa Role in hemostasis Balances procoagulant action–fibrinogenesis and fibrinolysis–protects fibrin Lab ↑ PTT–corrects when Pt's serum is mixed with equal volumes of normal plasma, normal PT Management Fresh frozen plasma. See Deep vein thrombosis, Fibrin, Intrinsic pathway, Thrombin.