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Unit Code 9290:
D-Dimer, Plasma

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Method Description

The specific degradation of fibrin (ie, fibrinolysis) is the reactive

mechanism responding to the formation of fibrin. Plasmin is the

fibrinolytic enzyme derived from inactive plasminogen. Plasminogen

is converted into plasmin by plasminogen activators. The main

plasminogen activators are tissue plasminogen activator (tPA) and

pro-urokinase which is activated into urokinase (UK) by, among

others, the contact system of coagulation.

 

In the bloodstream, plasmin is rapidly and specifically neutralized

by alpha 2-antiplasmin, thereby restricting its fibrinogenolytic activity

and localizes the fibrinolysis on the fibrin clot. On the fibrin clot plasmin

degrades fibrin into various products, (ie, D-dimers). Antibodies

specific for these products, which do not recognize fibrinogen, have

been developed. The presence of these various fibrin degradation

products, among which D-Dimer is the terminal product, is the proof

that the fibrinolytic system is in action in response to coagulation

activation.

 

The principle of the test is as follows. When a beam of monochromatic

light is allowed to transverse a suspension of microlatex particles to

which specific antibodies have been attached by covalent bonding

and if the wavelength of the light is much greater than the diameter of

the latex particles, the light is only slightly absorbed. In the presence

of the antigen being tested for, the antibody-coated latex particles

agglutinate to form aggregates of a diameter greater than the

wavelength of the light, more of the latter is absorbed. This increase

in light absorption is a function of the antigen level present in the test

sample. (Package insert:  STA-LIATEST D-DI, Diagnostica Stago, Inc.)

Performing Laboratory Location

Rochester

Key