D-dimer

Differential Diagnosis

• Factors that can cause false-negative D-dimer
  • Symptoms of PE > 3 days
  • Small PE
  • Use of qualitative latex fixation test
  • Use of anticoagulants
• Factors that can cause false-positive D-dimer
  • Cancer and malignancy
  • Recent surgery
  • Infection (eg, pneumonia, sepsis)
  • Pregnancy
  • Age > 70 years
  • DIC
  • Trauma
  • Arterial thrombosis
  • ACS/AMI
  • Vaso-occlusive sickle cell crisis
  • Acute CVA
  • Vasculitis
  • Superficial phlebitis

Evaluation

• Traditional cutoff value = 500
• Age-adjusted (for over 50 years old) = age x 10
  • Maintains high sensitivity while increasing specificity

See Also

• Age adjusted D-dimer
• Pulmonary embolism
• Deep venous thrombosis
• [[Pulmonary embolism in pregnancy|Evaluation]

External Links

• D-dimer threshold increase. Kline et. al.
• Pediatric Emergency Playbook Podcast: Big Labs, Little People