1.Prothrombin time 【PT】 Measure the exogenous pathway, vitamin K, Warfarin, etc. have an effect on it. Principle: Add prothrombin and calcium ions to sodium raffinate anticoagulated plasma, hold at 37 ℃, and measure plasma clotting time (PT). If the clotting time is prolonged, the plasma is deficient (or reduced) in one or more of the coagulation factors. This method is mainly used to screen for factors II, VII, and X, which are dependent on vitamin K in the exogenous coagulation pathway. In addition, abnormal results can occur in the absence of factor V and fibrinogen and in the presence of inhibitors of related factors. 2. Activated partial thromboplastin time [APTT] measures the endogenous system. Heparin has an effect on it. Principle A ceruloplasmin ( platelet substitute, i.e., partial thromboplastin ) and activator are added to plasma, and after holding, appropriate concentrations of calcium ions are added. The APTT is the time (in seconds) for the formation of fibrin clots and is used to screen for defects in endogenous and co-pathway coagulation factors such as Ⅻ, Ⅶ, Ⅸ, Ⅺ, PK, HMWK and fibrinogen. It is also used for the determination of inhibitors of these factors and for monitoring heparin therapy. Normal value range: 27-35 sec. The APTT is monitored during anticoagulation therapy with heparin and is maintained at 1.5-2.5 times normal. 3.Activated coagulation test [ACT] Also measures the endogenous system. Used at high doses of heparin to help regulate the amount of heparin. Principle: The addition of inert diatomaceous earth to blood can increase plasma contact activity and accelerate the blood clotting process, from the injection of blood into the test tube containing diatomaceous earth to the appearance of blood clots is ACT. determination of ACT can understand the endogenous coagulation pathway, but also the most useful indicators to monitor the level of heparin and fisetin dosage. The normal value of ACT with diatomaceous earth is 60-130 s. However, it varies widely and is influenced by many factors such as platelet count and function, fibrinogen level, temperature, peptidase and fisetin overload. 4.International Normalized Ratio [INR] is similar to PT, and the number is convenient for patients to remember and regulate. It is the standard ratio converted by PT, which can reflect the prothrombin time more accurately. WHO regulations with Warfarin (Farfarin) INR value allowed range: Pre-operative treatment: (non-hip surgery 1,5 ~ 2,5, hip surgery 2,0 ~ 3,0); prevention of venous thrombosis; 2,0 ~ 3,0; active venous thrombosis; (recurrent venous thrombosis, pulmonary embolism and its prevention 2,0 ~ 4,0); prevention of arterial thrombosis and embolism including heart valves (mechanical valve) surgery: 3 to 4, 5. When low molecular weight heparin is used, clinical monitoring is mostly not necessary unless the patient is obese (absorption) or has renal insufficiency (excretion). Because of its small effect on IIa, it is not measured with APTT and needs to be monitored with anti-Xa assay.