There are many causes of elevated D-dimer, such as inflammatory infections tumors, cerebral infarction, acute myocardial infarction, and pulmonary embolism may all cause elevated D-dimer secondary to D-dimer. If a patient currently has symptoms of coronary artery disease or angina pectoris and has elevated D-dimer, the D-dimer can be reduced by subcutaneous injection of low molecular heparin. If the patient currently has inflammatory infections in the lungs, or inflammatory infections in other areas, it is likely that the high D-dimer will improve better with effective anti-inflammatory therapy. Therefore, when D-dimer is elevated, it is important to first identify the cause of the disease so that we can guide how the next step should be treated. In addition to observing the D-dimer, the actual clinical symptoms of the patient should be taken into account, and the laboratory indicators of blood routine, lipids and blood glucose should be taken into consideration.