Gausman Jana N, Marlar Richard A
Pathology and Laboratory Medicine Service, Oklahoma City VA Medical Center, Oklahoma City, OK, USA.
Department of Pathology, University of New Mexico, Albuquerque, NM, 87131, USA.
Methods Mol Biol. 2017;1646:161-167. doi: 10.1007/978-1-4939-7196-1_13.
Antithrombin (AT) is a naturally occurring plasma inhibitor of coagulation, which is a synthesized in the liver. AT inhibits coagulation serine proteases (the enzymatically activated forms of the clotting factors), mainly thrombin (factor IIa) and factor Xa, but also to a lesser extent factors IXa, XIa, and XIIa. Acting alone, AT inhibits coagulation factors, but does this very slowly; however, when coupled with heparin as a cofactor, the speed of inhibition is increased many fold. The AT/Heparin complex is the most powerful naturally occurring anticoagulant in blood. AT levels of <70% of normal can cause significant thrombosis. Low levels of AT are caused by inherited genetic defects or acquired causes from other disease states. Plasma AT levels can be determined using a chromogenic assay with either bovine thrombin or human factor Xa as the enzyme. The generated color generated in the assay is inversely proportional to the concentration of AT in the plasma.
抗凝血酶（AT）是一种天然存在的血浆凝血抑制剂，由肝脏合成。AT抑制凝血丝氨酸蛋白酶（凝血因子的酶促活化形式），主要是凝血酶（因子IIa）和因子Xa，但在较小程度上也抑制因子IXa、XIa和XIIa。单独作用时，AT抑制凝血因子，但作用非常缓慢；然而，当与肝素作为辅因子结合时，抑制速度会提高许多倍。AT/肝素复合物是血液中最强大的天然抗凝剂。AT水平低于正常水平的70%可导致显著血栓形成。AT水平低是由遗传缺陷或其他疾病状态的后天原因引起的。血浆AT水平可以使用以牛凝血酶或人因子Xa作为酶的发色测定法来确定。测定中产生的颜色与血浆中AT的浓度成反比。
