Clotting factors:

  • 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.