Indicator Explainer
D-Dimer
A fibrin breakdown fragment — most useful for ruling out venous thromboembolism when clinical probability is low.
This page explains what the indicator is and how results are interpreted in general terms. Reference ranges depend on the laboratory, the method, and your own situation — no single “normal value” applies to everyone. This page is health information, not a diagnosis. For symptoms, treatment, or urgent concerns, contact a healthcare professional.
When it is tested
Measured in emergency pathways for suspected deep-vein thrombosis and pulmonary embolism, always in combination with validated clinical decision rules, and in some disseminated-intravascular-coagulation monitoring.
Reading results
A negative result on a validated assay is powerful for exclusion in low-probability patients; a positive result is common in the elderly, pregnant patients, post-operative and inflamed patients, and does not diagnose anything. Units (FEU vs DDU) and cutoffs differ between assays — including age-adjusted cutoffs — and must be read against the performing laboratory’s validation.
Questions to ask a professional
- Which clinical decision rule was applied before testing?
- Which units and cutoff does this assay use — and is an age-adjusted cutoff appropriate?
- What non-thrombotic causes of elevation apply to this patient?