Elevated plasma D-dimer is seen in pulmonary thromboembolism, deep vein thrombosis, diffuse intravascular coagulation, etc. It will decrease after treatment of the primary disease, such as anticoagulation, thrombolysis, etc. Serum D-dimer is a soluble degradation product of cross-linked fibrin produced by the action of the fibrinolytic system, which is highly sensitive to thrombosis. Serum D-dimer is a soluble degradation product produced by cross-linked fibrin under the action of fibrinolytic system, which has high sensitivity to the formation of thrombus, and the elevation of D-dimer is mainly caused by disease factors, such as cardiovascular system, thrombophilia and so on. 1. Thrombotic diseases: D-dimer will be elevated when deep vein thrombosis, pulmonary embolism, disseminated intravascular coagulation and other diseases occur. Take pulmonary embolism as an example, D-dimer will be elevated when it occurs, and the treatment is mainly through drugs, such as low molecular heparin, warfarin, rt-PA, urokinase and other anticoagulant thrombolytic therapy. 2. Cardiovascular diseases: myocardial infarction and cerebral infarction will also cause D-dimer elevation. Treatment options are anticoagulation, thrombolysis, antiplatelet therapy or percutaneous coronary intervention. Pregnancy in women can also cause elevation of plasma D-dimer, which decreases after pregnancy as the body gradually repairs itself. Patients with elevated D-dimer on examination should seek immediate medical attention for a definitive diagnosis and standardized treatment. The use of drugs must follow the doctor’s instructions, not blindly use their own drugs, in order to avoid adverse consequences.