Does an elevated D-dimer (D-dimer) level indicate a possible Deep Vein Thrombosis (DVT) or Pulmonary Embolism (PE)?

Elevated D-dimer and Its Relationship to DVT/PE

An elevated D-dimer level indicates a possible DVT or PE, but it cannot be used alone to diagnose these conditions due to its high sensitivity but low specificity. 1, 2

Understanding D-dimer in VTE Diagnosis

• D-dimer levels become elevated in plasma during acute thrombosis due to simultaneous activation of coagulation and fibrinolysis, making it a useful marker for ruling out VTE 1
• The negative predictive value of D-dimer testing is high, meaning a normal D-dimer level effectively rules out acute PE or DVT in patients with low clinical probability 2, 3
• The positive predictive value of elevated D-dimer is low because D-dimer can be elevated in many non-thrombotic conditions including cancer, inflammation, bleeding, trauma, surgery, and necrosis 1, 4
• Almost all patients with acute VTE have an elevated D-dimer level, but the test lacks specificity for VTE 3

Clinical Application in DVT/PE Diagnosis

• The European Society of Cardiology recommends using D-dimer measurement in emergency department patients to reduce unnecessary imaging, preferably using a highly sensitive assay 1
• D-dimer should not be used as the sole test to diagnose PE, especially in patients with high clinical probability, as a normal result does not safely exclude PE even with highly sensitive assays 1
• Higher D-dimer values predict increased likelihood of subsequent VTE diagnosis, with values >3,999 ng/mL associated with >50% likelihood of positive VTE findings 5
• For patients with suspected PE, the American Society of Hematology recommends using a strategy starting with D-dimer for excluding PE in populations with unlikely pre-test probability 1

Important Considerations and Limitations

• D-dimer specificity decreases with age, dropping to approximately 10% in patients >80 years old 1, 2
• Age-adjusted D-dimer cut-offs (age × 10 μg/L for patients >50 years) can improve diagnostic utility in older patients, increasing the number of patients in whom PE could be excluded 1, 2
• D-dimer has limited utility in hospitalized patients and certain populations (post-surgical, pregnant) due to high frequency of positive results with standard thresholds 1
• Tissue injury can cause persistently elevated D-dimer levels that may not normalize for extended periods, limiting its usefulness in trauma patients 6

Diagnostic Algorithm for Suspected VTE

1. Assess clinical probability using validated prediction rules (Wells score or revised Geneva score) 1, 2
2. For patients with low/intermediate clinical probability:
   • Perform D-dimer testing using a highly sensitive assay 1
   • If D-dimer is negative, VTE is excluded (no further testing needed) 1, 7
   • If D-dimer is positive, proceed to imaging studies 1
3. For patients with high clinical probability:
   • D-dimer testing is not recommended as even a negative result doesn't safely exclude PE 1
   • Proceed directly to appropriate imaging 1
4. Imaging selection:
   • For suspected PE: CT pulmonary angiography (CTPA) 1, 2
   • For suspected DVT: Compression ultrasonography 1

Remember that while an elevated D-dimer raises suspicion for DVT/PE, it must always be interpreted in the context of clinical probability and followed by appropriate imaging studies when positive or when clinical suspicion is high 1.