D-dimer levels are measured by latex immunoassay which employs latex particles coated with antibodies to D-dimers to capture D-dimers in the test plasma. The D-dimers act as a bridge between latex particles that leads to a degree of agglutination directly proportional to concentration, which is measured turbidimetrically.
Clinical details: 
Progressive degradation of cross-linked fibrin by plasmin leads to formation of small terminal derivates, one of which is D-dimer. Each D-fragment in a D-dimer molecule is derived from a different parent fibrin(ogen) molecule and remain joined due to cross-linking, so detection of D-dimers in plasma indicates the presence of a blood clot. Elevated D-dimers are a marker of reactive fibrinolysis and can be encountered in conditions such as DVT, PE & DIC. A normal D-dimer level has a high negative predictive value for DVT & PE.
Reference range: 

D-dimer cut off (mg/L FEU) according to age:

< 60 yrs                 -             <0.5

60 - 69 yrs            -              <0.6

70 - 79 yrs            -              <0.7

80 - 89 yrs            -              <0.8

> 90 yrs               -              <0.9

mg/L FEU
Sample type and Volume required: 
External requests: Citrated platelet poor plasma
400µL x 1 aliquot
Internal requests: please refer to EPR label

Turnaround time: 
4 hours
Special sample instructions: 

The sample should be analysed within 4 hours of venepuncture. Please ensure sample tubes are filled exactly to the fill-line as underfilling creates a dilution error and leads to inaccurate results

Diagnostic Haemostasis and Thrombosis Department
St Thomas': 020 7188 2797; Guy's: 020 7188 7188 ext. 53860
St Thomas' Hospital
North Wing - 4th and 5th Floors
Westminster Bridge Road
London SE1 7EH

Laboratory opening times

Guy's Hospital
Southwark Wing - 4th Floor
Great Maze Pond
London SE1 9RT

Outside core hours, contact Duty Haemostasis Biomedical Scientist
For clinical advice or interpretation of results, please contact the laboratory in the first instance.

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Last updated: 10/11/2021