- The clotting factors are a group of chemicals in the blood which is responsible for the formation of blood clot.
- Clotting factors are usually inactive but once there is an injury to the wall of the blood vessel, they get activated.
- The function of clotting factors is to trigger the formation of a blood clot and stabilize it for as long as necessary.
- Clotting factors are therefore known as procoagulants.
MNEMONIC for Clotting Factors:
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Factor I — Fibrinogen; common pathway; converted to fibrin.
Factor II — Prothrombin; common pathway; converted to thrombin that converts fibrinogen to fibrin.
Factor III — Tissue factor (TF) or thromboplastin; extrinsic pathway.
Factor IV — Calcium ions (Ca2+); always present, needed for coagulation.
Factor V — Labile factor, Proaccelerin; common pathway.
Factor VI — not used
Factor VII — Stable factor, Proconvertin; both extrinsic & intrinsic pathway.
Factor VIII — Antihaemophilic factor (AHF); intrinsic pathway: deficiency leads to hemophilia A.
Factor IX — Christmas factor, Plasma thromboplastin component (PTC); intrinsic pathway; deficiency leads to hemophilia B.
Factor X — Stuart-Prower factor; common pathway.
Factor XI — Plasma thromboplastin antecedent (PTA); intrinsic pathway; deficiency leads to hemophilia C.
Factor XII — Hageman factor; intrinsic pathway; activates plasmin.
Factor XIII — Fibrin stabilizing factor (FSF); common pathway; cross-links fibrin.
- Factor VIII & IX are sex-linked characters, others are autosomal.