凝血
凝血因子

凝血因子是参与血液凝固过程的各种蛋白质组分。它的生理作用是，在血管出血时被激活，和血小板粘连在一起并且补塞血管上的漏口。这个过程称为凝血。它们部分由肝生成。可以为香豆素所抑制。为统一命名，世界卫生组织按其被发现的先后次序用罗马数字编号，有凝血因子I，II，III，IV，V，VII，VIII，IX，X，XI，XII，XIII，XIII等，因子XIII以後被發現的凝血因子，經過多年驗證，認為對於凝血功能，無決定性的影響，不再列入凝血因子的編號。因子VI事實上是活化的第五因子，已經取消因子VI的命名。
除两个新发现的凝血因子外，其余的凝血因子按发现的先后顺序，由国际凝血因子命名委员会（International Committee on the Nomenclature of Blood Clotting Factors）以罗马数字统一命名。活化后的凝血因子，在其名字的右下方以字母“a”標示。
| 编号与/或名称 | 功能 | 相关遗传疾病 |
| --- | --- | --- |
| Ⅰ（纖維蛋白原） | 形成凝块（纤维蛋白） | 先天性纤维蛋白原缺乏血症、家族性腎澱粉樣變 |
| Ⅱ（凝血酶原） | 其活性形式（Ⅱa）激活Ⅰ、Ⅴ、Ⅹ、Ⅶ、Ⅷ、Ⅺ、XIII、蛋白C、血小板 | 凝血酶原G20210A、血栓形成倾向症 |
| Ⅲ（组织因子或组织促凝血酶原激酶） | Co-factor of VIIa (formerly known as factor III) |  |
| Ⅳ（钙） | Required for coagulation factors to bind to phospholipid (formerly known as factor IV) |  |
| Ⅴ（前加速素、易变因子） | Co-factor of X with which it forms the prothrombinase complex | Activated protein C resistance |
| VI | Unassigned – old name of Factor Va |  |
| VII (stable factor, proconvertin) | Activates IX, X | congenital factor VII deficiency |
| VIII（抗血友病因子甲） | Co-factor of IX with which it forms the tenase complex | 甲型血友病 |
| IX (Antihemophilic factor B or Christmas factor) | Activates X: forms tenase complex with factor VIII | Haemophilia B |
| X (Stuart-Prower factor) | Activates II: forms prothrombinase complex with factor V | Congenital Factor X deficiency |
| XI (plasma thromboplastin antecedent) | Activates IX | Haemophilia C |
| XII (Hageman factor) | Activates factor XI, VII and prekallikrein | Hereditary angioedema type III |
| XIII (fibrin-stabilizing factor) | Crosslinks fibrin | Congenital Factor XIIIa/b deficiency |
| 类血友病因子 | Binds to VIII, mediates platelet adhesion | von Willebrand disease |
| 前激肽释放酶 (Fletcher factor) | Activates XII and prekallikrein; cleaves HMWK | Prekallikrein/Fletcher Factor deficiency |
| 高分子量激肽原 (HMWK) (Fitzgerald factor) | Supports reciprocal activation of XII, XI, and prekallikrein | Kininogen deficiency |
| 纤连蛋白 | Mediates cell adhesion | Glomerulopathy with fibronectin deposits |
| 抗凝血酶 III | Inhibits IIa, Xa, and other proteases | Antithrombin III deficiency |
| heparin cofactor II | Inhibits IIa, cofactor for heparin and dermatan sulfate ("minor antithrombin") | Heparin cofactor II deficiency |
| 蛋白C | Inactivates Va and VIIIa | Protein C deficiency |
| 蛋白S | Cofactor for activated protein C (APC, inactive when bound to C4b-binding protein) | Protein S deficiency |
| 蛋白Z | Mediates thrombin adhesion to phospholipids and stimulates degradation of factor X by ZPI | Protein Z deficiency |
| Protein Z-related protease inhibitor (ZPI) | Degrades factors X (in presence of protein Z) and XI (independently) |  |
| 纤溶酶原 | Converts to plasmin, lyses fibrin and other proteins | Plasminogen deficiency, type I (ligneous conjunctivitis) |
| alpha 2-antiplasmin | Inhibits plasmin | Antiplasmin deficiency |
| 组织型纤溶酶原激活物 (tPA) | Activates plasminogen | Familial hyperfibrinolysis and thrombophilia |
| 尿激酶 | Activates plasminogen | Quebec platelet disorder |
| 纤溶酶原激活物抑制剂-1 (PAI1) | Inactivates tPA & urokinase (endothelial PAI) | Plasminogen activator inhibitor-1 deficiency |
| 纤溶酶原激活物抑制剂-2 (PAI2) | Inactivates tPA & urokinase (placental PAI) |  |
| cancer procoagulant | Pathological factor X activator linked to thrombosis in cancer |  |
在人类中，因子XI缺乏可能与出血表型有关。 因子XI也可能参与人类血栓形成，因为这种蛋白质的缺乏与缺血性中风风险降低相关，但与心肌梗塞风险降低无关。