From the Guidelines
A mildly elevated D-dimer test has a relatively low likelihood of indicating an actual blood clot, with studies suggesting that only about 10-25% of patients with elevated D-dimer levels actually have a clinically significant clot. D-dimer is a highly sensitive but not specific test, meaning it can detect clots when present but often gives false positives. Many conditions besides clots can cause mild D-dimer elevations, including inflammation, infection, pregnancy, recent surgery, advanced age, and cancer 1. The test's primary value is in its negative predictive power—a normal D-dimer can effectively rule out clots in low-risk patients.
Key Points to Consider
- The negative predictive value of D-dimer testing is high, and a normal D-dimer level renders acute PE or DVT unlikely 1.
- A mildly elevated D-dimer level should lead to imaging studies, but the interpretation of D-dimer results should always be done in the context of the overall clinical picture rather than as a standalone diagnostic tool 1.
- Clinical decision trees, such as the Wells criteria, have been developed and validated to estimate the pretest likelihood of PE, and D-dimer testing can be used in conjunction with these criteria to further stratify patients 1.
- The three-month thromboembolic risk was less than 1% in patients left untreated on the basis of a negative test result, confirming the safety of using D-dimer testing to rule out PE in low-risk patients 1.
Recommendations
- If you have a mildly elevated D-dimer, your doctor will likely consider your clinical risk factors and symptoms before deciding whether additional imaging tests like ultrasound or CT scans are necessary to confirm or exclude a clot.
- The use of age-adjusted D-dimer cutoffs may help increase the specificity of the test, particularly in patients older than 50 years 1.
- A normal plasma D-dimer level provides sufficient negative predictive value for PE, and no imaging studies are indicated in low-risk patients with a normal D-dimer level 1.
From the Research
D-Dimer Elevation and Adverse Outcomes
- A mildly elevated D-dimer level may be associated with an increased risk of incident venous thromboembolism (VTE), recurrent VTE, and mortality, as stated in the study 2.
- However, it is essential to note that a D-dimer within normal limits is used to rule out the diagnosis of deep venous thrombosis and pulmonary embolism among patients with a low clinical probability of VTE.
Diagnostic Value of D-Dimer
- The diagnostic value of D-dimer can be affected by various factors, including the administration of anticoagulants such as rivaroxaban, which may reduce the sensitivity and increase false negative results of the test 3.
- A high D-dimer level can be caused by various conditions, including physiologic conditions, such as aging, pregnancy, and strenuous physical activity, as well as several disorders, ranging from disseminated intravascular coagulation to infectious diseases and cancers 4.
Management of Elevated D-Dimer
- The management of a high D-dimer level involves a multifaceted approach, including clinical assessment, evaluation of pre-test probability, and objective diagnostic testing 5.
- If DVT is suspected, anticoagulation is indicated to control symptoms, prevent progression, and reduce the risk of post-thrombotic syndrome and pulmonary embolism, with direct oral anticoagulants (DOACs) being the preferred treatment for DVT 5.
Likelihood of a Clot
- While a mildly elevated D-dimer level may be associated with an increased risk of VTE, it is not a definitive indicator of a clot, and further diagnostic testing, such as compression ultrasound, may be necessary to confirm the presence of a clot 6, 5.
- Extremely elevated D-dimer levels (> 5000 μg/l) are uniquely associated with severe disease, mainly including VTE, sepsis, and/or cancer, but mildly elevated levels may have a broader range of causes 6.