About D-dimer
What is D-dimer
D-dimer is the smallest breakdown product
of clot dissolution. The coagulation cascade culminates in the
conversion of fibrinogen into fibrin and the development of a
insoluble fibrin clot. Complementary to the coagulation cascade Is
the process known as fibrinolysis. This is the body’s defence
mechanism against the permanent occlusion of blood vessels,
breaking down fibrin clots in order to restore blood flow. Plasmin
degrades the fibrin network of the clot releasing a number of
fibrin degredation products. D-dimer is the smallest
plasmin-resistant molecular unit of all the fibrin degradation
products. D-dimer is present in the circulation as part of the
normal wound healing process, however it is invaluable as a
diagnostic marker for thrombotic conditions such as DIC and as an
aid to the rule-out of DVT and PE.
The 3B6 Antibody
The only monoclonal antibody unique to
the D-dimer epitope is DD-3B6/22, more commonly known as 3B6.
Clearview Simplify D-dimer uses 3B6 which is highly specific for
D-dimer and does not cross-react with other fibrin degradation
molecules. This gives Clearview Simplify D-dimer high specificity
for D-dimer and aids the safe-rule out of patients.
DVT and PE Rule-Out Algorithms
D-dimer alone is not sufficiently
accurate to safely rule-out patients suspected of DVT or PE.
Diagnostic algorthims have been developed that comprise of a
pre-test probability score and D-dimer testing to safely rule out
DVT or PE. Perhaps the most famous of these are those developed by
Philip Wells,1, 2 although others exist. It is important
that any rule has been validated in the safe rule-out of VTE.
Clinical Information
Clearview Simplify D-dimer 100% sensitive in a 120
Outpatient Study with Suspected DVT3
Clearview Simplify D-dimer 100% sensitive in a 527 Outpatient
Study with Symptomatic PE4
Further studies demonstrate that Clearview Simplify D-dimer can
be safely used as an aid to rule-out of VTE when used in
conjunction with validated diagnostic algorithms.5,
6
The use of validated diagnostic algorithms, such as Wellls, in
combination with D-dimer testing have been determined as safe with
a post test probability of an event of less than
1%.7
References
- Kline JA, Wells PS. Methodology for a rapid protocol to rule
out pulmonary embolism in the emergency department. Ann Emerg Med
2003 Aug;42(2):266-75.
- Wells PS, Anderson DR et al. Evaluation of D-Dimer in the
diagnosis of suspected deep-vein thrombosis. N Engl J Med
2003;349:1227-35.
- Cini M, Legnani C, Cavallaroni et al. A new rapid bedside assay
for D-dimer measurement (Simplify D-dimer) in the diagnostic
work-up for deep vein thrombosis. J Thromb Haemost
2003;1:2681-3.
- Toulon P, Meynlad O. D-dimer testing in patients with suspected
pulmonary embolism. Performance of a new rapid semi-quantitative
solid-phase immunochromatography assay (Simplify D-dimer) and
comparison with two automated quantitative assays. Blood 2003;
102:1b-514b: Abstract no. 4149.
- Kline JA, Runyon MS, Webb WB et al. Prospective Study of the
Diagnostic Accuracy of the Simplify D-dimer Assay for Pulmonary
Embolism in Emergency Department Patients.
- Subramaniam, RM, Heath R, Cox K et al. Does an
immunochromatographic D-dimer exclude acute lowerlimb deep venous
thrombosis? Emerg Med Australas 2006;18:457-463.
- Wells PS, Owen C, Doucette S et al. Does this Patient have Deep
Vein Thombosis? JAMA 2006;295:199-206.