What is D-dimer?

D-dimer is the simplest degradation product of fibrin, and its elevated level can reflect the hypercoagulable state and secondary hyperfibrinolysis in vivo. D-dimer can be used as a marker of hypercoagulability and hyperfibrinolysis in vivo, and its increase suggests that it is related to thrombotic diseases caused by various reasons in vivo, and also indicates the enhancement of fibrinolytic activity.

Under what conditions are D-dimer levels elevated?

Both venous thromboembolism (VTE) and non-venous thromboembolic disorders can cause elevated D-dimer levels.

VTE includes acute pulmonary embolism, deep vein thrombosis (DVT) and cerebral venous (sinus) thrombosis (CVST).

Non-venous thromboembolic disorders include acute aortic dissection (AAD), ruptured aneurysm, stroke (CVA), disseminated intravascular coagulation (DIC), sepsis, acute coronary syndrome (ACS), and chronic obstructive Pulmonary disease (COPD), etc. In addition, D-dimer levels are also elevated in conditions such as advanced age, recent surgery/trauma, and thrombolysis.

D-dimer can be used to assess pulmonary embolism prognosis

D-dimer predicts mortality in patients with pulmonary embolism. In patients with acute pulmonary embolism, higher D-dimer values ​​were associated with higher PESI scores (Pulmonary Embolism Severity Index Score) and increased mortality. Studies have shown that D-dimer <1500 μg/L has a better negative predictive value for 3-month pulmonary embolism mortality: 3-month mortality is 0% when D-dimer <1500 μg/L. When D-dimer is greater than 1500 μg/L, high vigilance should be used.

In addition, some studies have shown that for patients with lung cancer, D-dimer <1500 μg/L is often an enhanced fibrinolytic activity caused by tumors; D-dimer >1500 μg/L often indicates that patients with lung cancer have deep vein thrombosis (DVT) and pulmonary embolism.

D-dimer predicts VTE recurrence

D-dimer is predictive of recurrent VTE. D-dimer-negative patients had a 3-month recurrence rate of 0. If D-dimer rises again during follow-up, the risk of VTE recurrence can be significantly increased.

D-dimer aids in diagnosis of aortic dissection

D-dimer has a good negative predictive value in patients with acute aortic dissection, and D-dimer negativity can rule out acute aortic dissection. D-dimer is elevated in patients with acute aortic dissection and not significantly elevated in patients with chronic aortic dissection.

D-dimer fluctuates repeatedly or suddenly rises, suggesting a greater risk of dissection rupture. If the patient's D-dimer level is relatively stable and low (<1000 μg/L), the risk of dissection rupture is small. Therefore, the D-dimer level can guide preferential treatment of those patients.

D-dimer and infection

Infection is one of the causes of VTE. During tooth extraction, bacteremia may occur, which may lead to thrombotic events. At this time, D-dimer levels should be closely monitored, and anticoagulation therapy should be strengthened when D-dimer levels are elevated.

In addition, respiratory infections and skin damage are risk factors for deep vein thrombosis.

D-dimer guides anticoagulation therapy

The results of the PROLONG multicenter, prospective study both in the initial (18-month follow-up) and extended (30-month follow-up) phases showed that compared with non-anticoagulated patients, D-dimer-positive patients continued after 1 month of interruption of treatment Anticoagulation significantly reduced the risk of VTE recurrence, but there was no significant difference in D-dimer-negative patients.

In a review published by Blood, Professor Kearon also pointed out that anticoagulation therapy can be guided according to a patient's D-dimer level. In patients with unprovoked proximal DVT or pulmonary embolism, anticoagulation therapy can be guided by D-dimer detection; if D-dimer is not used, the anticoagulation course can be determined according to the bleeding risk and the patient's wishes.

In addition, D-dimer can guide thrombolytic therapy.