Other causes and factors affecting raised D-dimer levels

Other conditions associated with a raised D-dimer include:

• D-dimer levels are raised in many systemic illnesses associated with fibrin formation and degradation
  • elevated levels of D-dimers occur in most critically ill patients with severe infection, trauma, or inflammatory disorders (1)
• in addition to venous thromboembolism, raised levels of circulating D-dimers are detected in patients with:
  • disseminated intravascular coagulation
  • vaso-occlusive sickle-cell crisis
  • acute cerebrovascular accident
  • acute myocardial infarction
  • unstable angina
  • atrial fibrillation
  • pneumonia
  • vasculitis
  • superficial phlebitis
  • many cancers including lung, prostate, cervical, and colorectal
  • note that only about 20% or less of patients admitted with these conditions will have a baseline D-dimer in the normal range (1)

Other factors affecting D-dimer levels:

• larger clots tend to produce a higher levels of circulating D-dimer
• there is an increase in circulating D-dimer levels with age, pregnancy, and smoking
• D-dimer levels may fail to increase if a patient has an acute venous thromboembolism, but impaired fibrinolytic activity
• D-dimer levels are reduced with initiation of heparin therapy, and may be lowered by two-thirds in patients on oral anticoagulants
• the time interval between onset of the acute venous thromboembolism and sample collection may affect the level of D-dimer detected
  • there may be normalisation of D-dimer levels with venous thromboembolism of longer than 7 days duration

Reference:

1. Sadosty AT et al. Emergency department D-dimer testing.Journal of Emergency Medicine December 2001;21(4):423-429