This lab quiz presents some practical case studies on the correct use of D-dimer tests in patients suspected of venous thromboembolism. Elevated D-dimer levels are associated with clotting activation and fibrinolysis and can be used as indirect biomarkers of thrombosis. The D-dimer test is highly sensitive and is used to rule out the presence of venous thromboembolism (VTE) when clinical probability is low, based on Wells scores. However, sensitivity and specificity of cut-off values for D-dimer for ruling out VTE are strongly assay-dependent due to lack of standardisation. Because of low specificity, use of these cut-off values is problematic in cases of sepsis and inflammation, after recent surgery and in cases of trauma and active malignancy as well as during anticoagulant therapy and pregnancy. Agedependent cut-off values for patients > 50 years old might improve specificity and could be safely used if clinically validated assays (latex-agglutination assays) are used as described for the ADJUST-study.
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