D-Dimer is one of the biomarkers with high attention on the market in recent years,

which is used to indicate thrombosis and thrombolytic activity in human body.

Let’s first talk about its clinical application.

1. Venous Thromboembolism (VTE)

the level of D-Dimer is significantly increased in VTE patients, however, some diseases such as cardiovascular disease, surgery, tumor, infection, and tissue necrosis also have a certain impact on blood clotting, which cause D-Dimer to increase. Therefore, the sensitivity of D-Dimer is 97%, but the specificity is around 61%-64%[1]. So D-Dimer can not be used to diagnose VTE alone. The practical significance of D-Dimer is that a negative result can exclude VTE.

2. Deep vein thrombosis (DVT)

a blood clot that's deep inside a vein. These clots usually affect the lower legs, but they can also happen in other parts of the body.

3. Pulmonary embolism (PE)

a blockage in an artery in the lungs. It usually happens when a blood clot in another part of the body breaks loose and travels to the lungs. DVT clots are a common cause of PE.

4. Disseminated intravascular coagulation (DIC)

DIC is a syndrome characterized by the systemic activation of blood coagulation, which generates intravascular fibrin, leading to thrombosis of small and medium-sized vessels, and eventually organ dysfunction. DIC may occur as a complication of infections, solid cancers, hematologic malignancies, obstetric diseases, trauma, aneurysm, and liver diseases, etc. International Society on Thrombosis and Haemostasis(ISTH) suggested that a reduced fibrinogen level is valuable for the diagnosis of DIC, but is not observed in most DIC patients. The elevated fiber-related markers (FRMs), such as fibrinogen and fibrin degradation products, D-dimers, and soluble fibrin (SF), reflect thrombin formation[3].

5. D-Dimer and COVID-19

Correlations exist between COVID-19 infection, severe elevation of D-dimer levels, and increase in the rate of complications and composite end-point. The appropriateness of early and continuous D-dimer monitoring and labeled anticoagulation as management tools for COVID-19 disease deserves accurate investigation, to prevent complications and reduce interventions[4].

Chinese Clinical Guidance for COIVD-19 Pneumonia Diagnosis and Treatment(7th edition) recommended that D-Dimer can be used for the diagnosis of severe COIVD-19 patients.

What is the best test method in detecting D-Dimer?

① Quantitative Test

② High specificity and negative predictive value

③ Good repeatability

④ The coefficient of variation is low when the result is at the critical level

⑤ Rapid and convenient

What could cause D-Dimer false negative?

① The volume of the thrombus is small or the distal small thrombus

② Fibrinolytic activity is decreased

③ Unreasonable design of reference interval and threshold

④ There are problems with sample preparation

In summary, a rapid, convenient, and quantitative D-Dimer test with high sensitivity has been widely used in the past 20 years. Its greatest value is that negative result is used as the diagnostic criteria of exclusion of suspected VTE or DIC patients. D-Dimer plays an important role in the prognosis of COVID-19 patients.

Reference:

[1] Sanjeev D. Chunilal, MB, ChB; Patrick A. Brill-Edwards, MD; Pamela B. Stevens, RN; et al, The Sensitivity and Specificity of a Red Blood Cell Agglutination D-Dimer Assay for Venous Thromboembolism When Performed on Venous Blood, Arch Intern Med. 2002;162(2):217-220. doi:10.1001/archinte.162.2.217.

[2] Taylor FB, Toh CH, Hoots WK, Wada H, Levi M. Towards definition, clinical and laboratory criteria, and a scoring system for disseminated intravascular coagulation. Thromb Haemost 2001; 86: 1327–30.

[3] H. Wada,* J. Thachil, M. DI Nisio, P. Mathew, S. Kurosawa, S. Gando, H.K. Kim, J.D. Nielsen, C-E. Dempfle, M. Levi, § C-H. Toh, The scientific and standardization committee on DIC of the ISTH

[4] Sofia Vidali, Daniele Morosetti, Elsa Cossu, Maria Luisa Eliana Luisi, Silvia Pancani, Vittorio Semeraro, Guglielmo Consales, D-dimer as an indicator of prognosis in SARS-CoV-2 infection: a systematic review, ERJ Open Research 2020 6: 00260-2020; DOI: 10.1183/23120541.00260-2020.