Fibrin degradation product D-dimer (D-dimer) (D-dimer)

Fibrin degradation product D-dimer is a protein fragment produced during the process of fibrinolysis, specifically when plasmin cleaves cross-linked fibrin [1]. It consists of two D domains from adjacent fibrin molecules that have been covalently cross-linked by Factor XIIIa, making it a specific marker for the degradation of stabilized fibrin clots rather than fibrinogen [2]. In clinical practice, D-dimer is primarily utilized as a high-sensitivity, low-specificity biomarker to rule out venous thromboembolism (VTE), including deep vein thrombosis (DVT) and pulmonary embolism (PE) [3]. Elevated levels are also observed in conditions such as disseminated intravascular coagulation (DIC), pregnancy, malignancy, and severe infections like COVID-19 [4]. While it is not a traditional therapeutic target for drug intervention, it serves as a critical diagnostic tool for monitoring coagulation status and treatment efficacy in thrombotic disorders [5]. The presence of D-dimer in the circulation indicates that a clot has formed and is subsequently being broken down by the body's natural enzymatic processes [1]. Sources: [1] StatPearls: D-dimer (https://www.ncbi.nlm.nih.gov/books/NBK441964/) [2] NIH/NCBI: D-dimer testing (https://pubmed.ncbi.nlm.nih.gov/19158210/) [3] Journal of the American College of Cardiology: D-dimer in VTE (https://www.jacc.org/doi/10.1016/j.jacc.2017.09.024) [4] Lancet: COVID-19 and D-dimer (https://www.thelancet.com/journals/lancet/article/PIIS0140-6736(20)30566-3/fulltext) [5] Blood: Clinical use of D-dimer (https://ashpublications.org/blood/article/113/13/2878/25411/The-D-dimer-assay-past-present-and-future)

Other names

Fibrin / fibrin degradation product DDFragment D-dimerCross-linked fibrin degradation productFDP D-dimer

D-dimer is formed by the sequential action of three enzymes: thrombin, which converts fibrinogen to fibrin; factor XIIIa, which cross-links the fibrin; and plasmin, which degrades the cross-linked fibrin. It is not a therapeutic target but a byproduct of clot degradation.