D-dimer
CoagulationNormal range
< 0.4 µg/mL FEU (lab-specific)
SI: < 0.4 mg/L FEU
☎ When to call
The symptoms escalate, not the number: sudden dyspnea, pleuritic pain, tachycardia + hypoxia = possible PE — rapid response, don't wait on labs.
What you do
- A negative d-dimer is more useful than a positive one — positive just means 'clot lysis somewhere'
- Positive with dyspnea/chest pain/unilateral leg swelling: anticipate imaging (CTA, doppler)
Causes of HIGH d-dimer
Causes of LOW d-dimer
Source: Pagana, Mosby's Manual of Diagnostic and Laboratory Tests, 7th ed.Reference only — verify against your facility's policy.
