Information AboutD-dimer |
| CATEGORIES ABOUT D-DIMER | |
| chemical pathology | |
| hematology | |
| fibrinolytic system | |
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INDICATIONS D-dimer testing is of clinical use when there is a suspicion of Deep Venous Thrombosis (DVT) or Pulmonary Embolism (PE). In patients suspected of Disseminated Intravascular Coagulation (DIC), D-dimers may aid in the diagnosis. For DVT and PE, there are various scoring systems that are used to determine the ''a priori'' clinical probability of these diseases; the best-known were introduced by Wells ''et al'' (2003).
REFERENCE RANGE Most sampling kits have 0-300 Ng / Ml as normal range. Values exceeding 250, 300 or 500 ng/ml (different for various kits) are considered positive. TYPES OF ASSAYS
PRINCIPLES Fibrin Degradation Product s (FDPs) are formed whenever Fibrin is Broken Down by Enzyme s (e.g. Plasmin ). Determining FDPs is not considered useful, as this does not indicate whether the fibrin is part of a blood clot (or being generated as part of Inflammation ). D-dimers are unique in that they are the breakdown products of a fibrin mesh that has been stabilised by Factor XIII . This factor crosslinks the E-element to ''two'' D-elements. This is the final step in the generation of a thrombus. Plasmin is a natural Fibrinolytic enzyme that organises clots and breaks down the fibrin mesh. It cannot, however, break down the bonds between one E and two D units. The protein fragment thus left over is a D-dimer. D-dimer assays rely on Monoclonal Antibodies to bind to this specific protein fragment. The first patented MoAb of the kind was ''D Dimer-3B6/22'', although others have been developed. SENSITIVITY AND SPECIFICITY Various kits have a 93-95% sensitivity and about 50% specificity in the diagnosis of thrombotic disease (Schrecengost ''et al'' 2003).
HISTORY D-dimer testing was originally developed in the diagnosis of disseminated intravascular coagulation. In the 1990s , they turned out to be useful in thromboembolic disorders. REFERENCES
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