Age-Adjusted D-dimer Threshold
Enter patient age and D-dimer result. The calculator converts units and compares to the age-adjusted cutoff (Age × 10 µg/L FEU) for patients older than 50 years.
Age-adjusted cutoff
680 µg/L FEU
Age × 10 for ages >50; 500 µg/L for ≤50.
Cutoff in selected units
680.00 µg/L (FEU)
Result
Below threshold
How to Use This Calculator
Confirm low clinical probability
Use validated pre-test probability tools (e.g., Wells score). Age-adjusted D-dimer is intended for low or intermediate risk patients.
Enter lab values with correct units
Match the unit exactly as reported (FEU vs DDU). The calculator converts as needed before applying the age-adjusted cutoff.
Interpret alongside clinical context
If D-dimer is ≤ age-adjusted threshold, VTE can be ruled out without imaging. If greater, proceed with imaging per guidelines.
Formula
Age-adjusted cutoff (µg/L FEU) = Age × 10 for age >50
For ages ≤50, standard cutoff = 500 µg/L FEU
Conversion: 1 mg/L FEU = 1000 µg/L FEU; 1 µg/L DDU ≈ 2 µg/L FEU
Full Description
D-dimer testing is sensitive but nonspecific for venous thromboembolism. In older adults, baseline D-dimer rises, producing false positives. Age-adjusted thresholds (Age × 10 µg/L FEU) improve specificity while maintaining safety when used with validated pre-test probability assessments. Adoption reduces unnecessary imaging and radiation exposure in emergency and outpatient settings.
Frequently Asked Questions
Who qualifies for age-adjusted D-dimer?
Adults over 50 years with low or intermediate pre-test probability of pulmonary embolism or DVT. Not validated for high-risk patients.
What if my lab reports DDU?
Select µg/L (DDU). The calculator doubles the value to convert to FEU equivalence before applying the threshold.
Can I use this in hospitalized patients?
Caution: age-adjusted D-dimer has mainly been studied in outpatients. Inpatients often have elevated baseline levels reducing utility.
Does anticoagulation affect interpretation?
Recent anticoagulation may lower D-dimer levels. Interpret results in context of treatment timing and ongoing symptoms.