Clinically, dimer is generally referred to as D-dimer, and its elevation can be seen as a precursor to a number of hematologic diseases, malignant tumors, thrombosis, and other diseases. Elevated D-dimer is commonly seen in disseminated intravascular coagulation, acute promyelocytic leukemia, and pulmonary thromboembolism. D-dimer values are also elevated when there is bleeding in the organism. The plasma D-dimer assay test is a common clinical screening test that reflects the activity of the human fibrinolytic system. The test has a high sensitivity and a low specificity, meaning that its elevation does not establish that the disease is definitely present, but its normal measurement can rule out diseases such as deep vein thrombosis or pulmonary embolism. The diagnosis of these diseases also needs to be integrated with the results of other auxiliary tests and requires further judgment by the clinician.