D-dimer is a commonly used clinical indicator for monitoring coagulation and thrombosis, and can be measured without fasting.D-dimer is a degradation product of fibrin, and the production and elevation of D-dimer reflects the activation of the coagulation and fibrinolytic systems in the body. Elevated plasma levels of D-dimer can reflect thrombin activity and fibrinogen production, and is an indicator of thrombosis.Elevated levels of D-dimer are commonly associated with secondary hyperfibrinolysis, such as diffuse intravascular hemolysis, rejection of organs after transplantation, cerebral infarction, myocardial infarction, and venous thrombosis. In addition, severe infections can also cause elevated D-dimer, which is an emergency test that can be done at any time and does not require fasting.