Elevated D-dimer is a normal product of human metabolism and is usually an intermediate molecule produced during thrombosis. elevated D-dimer does not necessarily indicate thrombotic disease, because some anticoagulation mechanisms and fibrinolytic system in the body will directly fibrinize microscopic thrombi in addition to thrombosis, so elevated D-dimer does not indicate thrombotic disease. In clinical practice, it is generally used as a diagnosis to exclude thrombotic disease, and is most often used in the exclusion diagnosis of acute pulmonary embolism. If the D-dimer is negative or not increased, it can be assumed that there is no thrombosis in the body; on the contrary, if the D-dimer is increased, it may be thrombosis, but it does not represent thrombotic disease, and it is possible that the fibrinolytic system fibrates some tiny thrombi. Therefore, there is no need to worry about the increase of D-dimer, which means that thrombotic diseases are not excluded. In this case, it is recommended to go to the hospital to investigate the related diseases and treat them according to the process of diseases.