Factor XIII (fibrin-stabilizing factor) (FXIII)

Factor XIII, also known as fibrin-stabilizing factor, is a transglutaminase enzyme activated by thrombin (FXIIIa) during the final stage of the coagulation cascade. It cross-links fibrin polymers into a stable, insoluble network that mechanically reinforces the initial platelet plug formed in primary hemostasis, preventing premature clot dissolution and enabling effective wound sealing. This stabilization is critical for hemostasis, as FXIIIa introduces covalent bonds between fibrin strands and alpha-2-antiplasmin, enhancing resistance to fibrinolysis by plasmin. Deficiencies in Factor XIII lead to severe bleeding disorders, such as congenital FXIII deficiency, characterized by intracranial hemorrhages and poor wound healing, while overactivity contributes to thrombotic diseases like myocardial infarction by forming rigid clots resistant to breakdown. Therapeutically, Factor XIII is targeted with replacement therapies for deficiencies and explored for inhibitors in antithrombotic strategies, though challenges include balancing clot stability against bleeding or thrombosis risks. Overall, it serves as a key regulator of clot mechanics in cardiovascular health.

Other names

Fibrin-stabilizing factorFibrinoligaseCoagulation factor XIIIPlasma transglutaminase

FXIIIa cross-links fibrin polymers to form mechanically stable clot network; Inhibitors prevent excessive cross-linking to reduce thrombosis risk