D-dimer - origin and clinical significance

Abstract

Introduction. D-dimer is formed during plasmin-mediated proteolysis of cross-linked fibrin; hence it serves as a biomarker of activated coagulation and fibrinolysis. Clinical significance. Measurement of D-dimer is most commonly used to exclude venous thromboembolism, and in the diagnosis of disseminated intravascular coagulation. For the diagnosis of venous thromboembolism D-dimer is part of the validated algorithm, which includes an assessment of clinical pre-test probability to guide further investigation. Due to very high negative predictive values, average levels of D-dimer are sufficient for ruling out venous thromboembolism in patients with low-medium pre-test clinical probability. However, in patients with high pre-test probability, the measurement of D-dimer is of limited value. Similarly, normal values of D-dimer reliably exclude disseminated intravascular coagulation. On the other hand, elevated values of D-dimer have low specificity for this condition and should be evaluated in a validated scoring system developed for the diagnosis of disseminated intravascular coagulation. Recently, measurement of D-dimer has been increasingly applied to assess the risk of venous thrombosis recurrence in women and to decide on the duration of anticoagulant therapy after the first unprovoked venous thrombosis. Elevated D-dimer level is an essential characteristic of COVID-19 - associated coagulopathy. The degree of coagulopathy and D-dimer levels correlate with the clinical severity of the disease and higher mortality, most likely reflecting increased activation of the coagulation system in the microcirculation of various organs, primarily the lungs. Conclusion. D-dimer is one of the most often used hemostasis test, validated so far for diagnosis of venous thromboembolism and disseminated intravascular coagulation.