D-dimer
D-dimer is a commonly tested biological marker which is produced by the enzymatic breakdown of cross-linked fibrin which forms the fibrous mesh of a blood clot. The measurement of D-dimer in the circulation acts as a marker of coagulation and fibrinolysis, which can be useful in the diagnosis of multiple diseases.
Validated uses of D-dimer
- excluding the diagnosis of pulmonary embolism or venous thromboembolism using various clinical decision tools:
- determining the optimal duration of anticoagulation therapy in patients with venous thromboembolic disease
- D-dimer in addition to platelet count, prothrombin time and fibrinogen can be used to diagnose and monitor disseminated intravascular coagulation (DIC)
- determining patients at high risk for thrombosis who have cancer or are hospitalized for other reasons
Unvalidated uses of D-dimer
- predicting the risk of stroke in patients with atrial fibrillation
- ruling out aortic dissection in low-risk patients (ADD-RS plus D-dimer)
- helping predict cardiovascular risk in HIV infected patients
Conditions associated with a raised D-dimer
- stroke, venous thromboembolic disease, atrial fibrillation, aortic dissection and disseminated intravascular coagulation
- normal pregnancy
- increasing age (age-related adjustments should be made)
- pre-eclampsia and eclampsia
- severe liver disease
- malignancy
- congestive cardiac failure
- renal disease
- sickle cell disease
- any surgery or trauma
- sepsis
- fibrinolytic therapy
- venous malformations
- acute allergic reactions
- including anaphylaxis, urticaria, mild allergic reactions
- pulmonary sarcoidosis: D-dimer level correlated to activity/stage of disease , not currently used as a disease marker
Conditions associated with an extremely high D-Dimer
In a recent large study an extreme elevated level was arbitrarily defined as >5,000 µg/L . The vast majority of cases were associated with severe disease:
- malignancy
- sepsis
- venous thromboembolism
- others
- trauma, surgery, aortic dissection/aneurysm,
