Plasma D-dimer is a product of fibrinolysis and is an important indicator of coagulation factors, often used to diagnose the presence of deep vein thrombosis, pulmonary embolism and other diseases, the normal value is usually in the range of 0-0.256 mg/L. If the plasma D-dimer is greater than 0.3 mg/L, it is usually called increased D-dimer, the more common causes of elevated plasma D-dimer are as follows: 1, thrombotic diseases: such as lower extremity deep vein thrombosis, pulmonary embolism, acute myocardial infarction, cerebral infarction, etc. 1, thrombotic diseases: such as lower limb deep vein thrombosis, pulmonary embolism, acute myocardial infarction, cerebral infarction, etc., may lead to elevated plasma D-dimer; 2, systemic diseases: such as diffuse intravascular coagulation, malignant tumors, acute promyelocytic leukemia, severe hepatitis, cirrhosis, etc., may also see elevated plasma D-dimer; 3, drug effects: some drugs such as estrogen may also cause coagulation Some drugs such as estrogen may cause abnormalities in blood clotting function, resulting in increased plasma D-dimer. In addition, some women during pregnancy may have elevated plasma D-dimer. However, if the patient has an old blood clot, plasma D-dimer may not be elevated. Testing for changes in plasma D-dimer values can also be used to determine the effectiveness of thrombolytic therapy.