d-dimer Assay
Haematology Overview / Directory
Purpose of the test
Activation of the coagulation process will lead to the cleavage of fibrinogen to fibrin. The fibrin molecule that results will be cross-linked via D-domain by Factor XIII, producing a stable fibrin clot.
Exacerbation of this process can lead to major clot and thrombi formation, which, if not controlled, can be fatal. Activation of the fibrinolytic system results in the conversion of plasminogen into the active protease, plasmin. Plasmin cleaves fibrinogen and fibrin into fragments D and E. Plasmin will release fibrin degradation products with cross-linked D-domains, the smallest unit of which is the D-dimer. Thus, detection of D-dimers is an indication of reactive fibrinolysis.
Elevated levels of D-dimer is indicative of the presence of a clot and has been reported in certain pathological conditions such as Pulmonary Embolism (PE), Deep Vein Thrombosis (DVT), and Disseminated Intravascular Coagulation (DIC).
Reference Range
Normal range: <500ng/ml FEU
Sample Requirements
One tri-sodium citrate sample.
Storage and Transport
If the assay will not be performed the same day, double spin citrate sample, remove the plasma and store in a capped plastic tube in –40°C freezer. This is stable for 1 month. Thaw for 10 minutes at 37°C, and perform the assay within 2 hours.
Turnaround Time
2 hours maximum
Time Limit for Extra Tests
4 hours
Factors affecting results or interpretation
Clots of any size , haemolysis, underfilling or overfilling will affect result.
Contacts
Haemostasis Laboratory on 020 3299 9000 ext 2434
email: liz.ford@nhs.net
