Venous thromboembolism (VTE) has an incidence rate in the UK of 1 in 1000 per annum, killing more people than breast cancer, road traffic accidents and AIDS combined. VTE accounts for approximately 25,000 in-hospital deaths in the UK prompting the National Institute for Clinical Excellence to recommend that every patient should be assessed for their risk of thromboembolism upon admission to hospital. A combination of the Wells score, routine coagulation screening and specialist testing is used depending of the clinical presentation of the patient.
Homeostatic fibrin degradation occurs when a fibrin clot is formed. This fibrin mesh is broken down by plasmin during a process called fibrinolysis. During fibrinolysis fibrin is cleaved at a different point to which it polymerises resulting in two crosslinked D fragments from separate fibrin proteins being released. This is a D-dimer protein. The amount of D-dimer present in a patient’s serum is directly proportional to recent fibrinolytic activity as the half life of a D-dimer is 4-6 hours.
D-dimers are produced in response to any fibrinlytic activity therefore they should not be used as the sole diagnostic indicator when assessing a patient for a VTE. D-dimer levels are known to increase in response to heavy exercise, infection and trauma in addition to VTE. The true diagnostic potential of the D-dimer test is in its negative predictive value. A normal D-dimer level can accurately exclude the diagnosis of VTE based on the absence of significant levels of fibrinolysis. A raised D-dimer level indicates the need for further investigations based on the clinical picture of the patient.
The current gold standard methodology for quantification of D-dimer is to use an ELISA method, however this is time–consuming and requires a dedicated analyser. In recent years immunoturbidimetry has been employed to quantify D-dimer levels based on agglutination of antibody–coated latex particles. Results show comparable performance to ELISA based tests, however higher throughput and greater flexibility are achieved allowing application of this test on multiple analysers.
Recognising the significant benefits of the latex-based assays for both the hospital and the patient but understanding the different complexities and limitations of the vast platform of coagulation analysers, Helena Biosciences Europe have applied our reagent manufacturing skills and invested in the development of appropriate reagents tailored to each specific platform.
Helena currently provide three bespoke D-dimer reagent types in our Auto Blue/Red D-dimer portfolio, each kit is available in multiple formats to suit the throughput of any lab. We support D-dimer testing on all major platforms including Instrumentation Laboratory, Siemens/Sysmex, Clinical Chemistry Analysers and many more. Also available is a manual latex-based method for areas without mainline analysers but requiring immediate turnaround of samples in a point of care environment
With a quick test time of approximately 5 minutes, multiple kit formats available, a sensitivity of 95% and a negative predictive value of 98%. The Helena Biosciences D-dimer assay is an ideal choice for D-dimer quantification in the modern laboratory.
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