Blood Coagulation Diseases and D-Dimer

Blood coagulation diseases are common hematological conditions, especially among the middle-aged and elderly population, and they can pose significant health risks. The diagnosis of these diseases requires a variety of methods, including the use of D-dimer, which plays a crucial role in diagnosis, evaluation of treatment efficacy, and prognosis assessment. However, patients may not be well-informed about D-dimer. Therefore, let's explore what D-dimer is and its clinical significance.

What is D-Dimer?

Fibrin is present in the blood, and through activation and hydrolysis, it produces specific degradation products known as "fibrin degradation products." D-dimer is the simplest fibrin degradation product, and an elevated level of D-dimer indicates a hypercoagulable state and secondary fibrinolytic hyperactivity within the body. Consequently, the concentration of D-dimer is significant for the diagnosis, treatment evaluation, and prognosis of blood coagulation diseases. Under normal physiological conditions, the body maintains a dynamic balance between fibrinolytic enzymes and inhibitory enzymes, allowing blood to flow normally in the vessels without coagulation or thrombosis. However, when abnormal factors lead to coagulation or thrombus formation, the fibrinolytic system is activated, degrading fibrin into fragments, which are then connected by a substance called D-dimer. Therefore, D-dimer is a sensitive marker for acute thrombus formation.

Clinical Significance of D-Dimer

D-dimer originates from the fibrin clot dissolved by fibrinolytic enzymes and primarily reflects fibrinolytic function. Clinical testing of D-dimer is primarily used in the diagnosis of venous thromboembolism (VTE), deep vein thrombosis (DVT), and pulmonary embolism (PE). Elevated levels of D-dimer are observed in conditions associated with secondary fibrinolytic hyperactivity, such as hypercoagulable states, disseminated intravascular coagulation, kidney diseases, organ transplant rejection, thrombolytic treatment, etc. Additionally, myocardial infarction, cerebral infarction, pulmonary embolism, venous thrombosis, surgery, cancer, diffuse intravascular coagulation, infection, and tissue necrosis can also lead to an increase in D-dimer levels.