For patients over 50 with non-high clinical probability of pulmonary embolism, the age-adjusted D-dimer cut-off is age × 10 ng/mL (fibrinogen-equivalent units) instead of the fixed 500. A 75-year-old's threshold is therefore 750. The alternative YEARS-type approach uses 1,000 ng/mL when no YEARS items are present (clinical DVT signs, haemoptysis, PE the most likely diagnosis) and 500 when any are. Neither applies to high clinical probability, where imaging is needed regardless of D-dimer.
- Assess clinical probability first (Wells or YEARS); do not use D-dimer alone in high-probability patients.
- Over 50: threshold = age × 10 ng/mL FEU.
- Check which units your laboratory reports — FEU versus D-dimer units differ by about twofold.
- Document the threshold used in the notes.
Why it matters
It is the simplest way to cut unnecessary CT pulmonary angiography in older patients.
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