Italiano
D DIMERO |
D-Dimer is a fibrin degradation product (FDP), a protein fragment that can be detected in the blood in the case of fibrinolysis, thanks to the action of the plasmin, a proteolytic enzyme. The name of the substance derives from the fact that it consists of two fibrin fragments D, stabilized by covalent crimson bonds. The molecular weight of D-Dimer is around 180,000 dalton and half life is 4-6 hours.
His determination by a blood test was introduced in the nineties and today it finds a clinical indication in the diagnosis of pulmonary embolism, deep venous thrombosis, and intravascular coagulation disseminated. The measurement has high sensitivity but low specificity, therefore a low value can exclude thromboembolic pathology, while a high value is not sufficient to determine its diagnosis.
D-Dimer is theoretically not normally present in the plasma of human blood, except when the coagulation system is activated, such as in the case of thrombosis or disseminated intravascular coagulation. In fact a low concentration of D-dimer can also be found in the blood of healthy subjects. This indicates that there is a dynamic balance between the fibrin formation phase and its degradation by the fibrinolytic system, even under physiological conditions.
Thus, the concentration of D-dimer in vivo reflects the condition of what may be termed hemostatic balance , and thus has a marked variability from individual to individual, whether it is healthy or suffering from pathological conditions.
Conditions D-Dimer Increase
Physiological: Advanced Age (Increase in Elderly> 65 years, possibly related to less mobility and atherosclerosis), Neonatal Period, Pregnancy (Expression of Enhanced Hypercoagulability of Condition), Laboratory Limits interference of plasma proteins, hemolysis, cross-reactants, antibodies).
Pathologic: Serious and seriously ill subjects, Infections in progress (Gram-negative sepsis!), Major traumas, Ictus, Heart failure, Neoplasms, Dissolved Intravascular Coagulation (CID), Surgical Interventions, Liver Diseases, Diseases kidney stones, chronic inflammatory diseases (Lupus erythematosus, rheumatoid arthritis), venous thromboembolism, thrombolytic therapy
Special Cases
False Positives: They may be due to various causes: liver disease, high rheumatoid factor, inflammation, malignant tumors, traumas, pregnancy, recent surgery, as well as advanced age.
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False Negatives: In particular, if the sample is harvested too soon after the formation of the thrombus or if the test is performed with a serious delay (in the order of several days), current anticoagulant treatment, sample test insufficiently.
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In elderly patients, D-dimer has a reduced specificity and therefore is less useful. However, it is possible to create age-dependent cut-off values in order to adapt and make useful test execution even in elderly subjects.
Physiological: Advanced Age (Increase in Elderly> 65 years, possibly related to less mobility and atherosclerosis), Neonatal Period, Pregnancy (Expression of Enhanced Hypercoagulability of Condition), Laboratory Limits interference of plasma proteins, hemolysis, cross-reactants, antibodies).
Pathologic: Serious and seriously ill subjects, Infections in progress (Gram-negative sepsis!), Major traumas, Ictus, Heart failure, Neoplasms, Dissolved Intravascular Coagulation (CID), Surgical Interventions, Liver Diseases, Diseases kidney stones, chronic inflammatory diseases (Lupus erythematosus, rheumatoid arthritis), venous thromboembolism, thrombolytic therapy
Special Cases
False Positives: They may be due to various causes: liver disease, high rheumatoid factor, inflammation, malignant tumors, traumas, pregnancy, recent surgery, as well as advanced age.
-
False Negatives: In particular, if the sample is harvested too soon after the formation of the thrombus or if the test is performed with a serious delay (in the order of several days), current anticoagulant treatment, sample test insufficiently.
-
In elderly patients, D-dimer has a reduced specificity and therefore is less useful. However, it is possible to create age-dependent cut-off values in order to adapt and make useful test execution even in elderly subjects.
Special Cases
False Positives: They may be due to various causes: liver disease, high rheumatoid factor, inflammation, malignant tumors, traumas, pregnancy, recent surgery, as well as advanced age.
-
False Negatives: In particular, if the sample is harvested too soon after the formation of the thrombus or if the test is performed with a serious delay (in the order of several days), current anticoagulant treatment, sample test insufficiently.
-
In elderly patients, D-dimer has a reduced specificity and therefore is less useful. However, it is possible to create age-dependent cut-off values in order to adapt and make useful test execution even in elderly subjects.
False Positives: They may be due to various causes: liver disease, high rheumatoid factor, inflammation, malignant tumors, traumas, pregnancy, recent surgery, as well as advanced age.
False Negatives: In particular, if the sample is harvested too soon after the formation of the thrombus or if the test is performed with a serious delay (in the order of several days), current anticoagulant treatment, sample test insufficiently.
In elderly patients, D-dimer has a reduced specificity and therefore is less useful. However, it is possible to create age-dependent cut-off values in order to adapt and make useful test execution even in elderly subjects.
