Indications of the D.Dimer . test

D.Dimer is the factor that demonstrates the presence of fibrin in the circulation. The D.Dimer test is often used to diagnose established venous thrombosis, disseminated intravascular coagulation, as well as monitor thrombotic pathology over time.

Normally in the human body, the process of blood clot formation and clot dissolution will always be in balance. However, if this process is just out of balance, it will cause many risks for the patient (such as thrombosis if excessive fibrin is produced or bleeding complications when fibrinolysis).
Plasma D.Dimer is a degradation product of fibrin formed under the action of Plasmin. This product will normally appear in the blood plasma, and is responsible for instructing the mechanism of blood clot formation and thrombin. Although D.Dimer is only an indirect marker of activated fibrinolysis, however, D.Dimer is useful when coagulation occurs.
Meanwhile, both fibrinogen and fibrin degradation products do not indicate the exact source of their degradation from fibrinogen or from fibrin, so the D.Dimer test will use monoclonal antibodies for specific identification. fibrin degradation products. Currently, there are 2 techniques for testing D.Dimer applied:
Test of D.Dimer condensate on Latex: This technique usually has low sensitivity, the reason is because the test only detects when there is a lot of blood. block formed. In case there is only 1 thrombus, the result is still negative. Therefore, the D.Dimer concentration test on Latex is considered as a sensitive and specific test for the diagnosis of disseminated vascular thrombosis in the lumen. Super sensitive D.Dimer test: The super sensitive D.Dimer test technique is conducted by ELISA or immunoturbidity measurement for the purpose of determining D.Dimer concentration. This ultra-sensitive test is very sensitive, even in the case of a single, small thrombus, it still gives a positive result.

D.Dimer is a factor that demonstrates the presence of fibrin in the circulation, therefore, this test is often used to:
Diagnosis of thrombosis: About 90% of cases have venous thrombosis. deep and 95% with pulmonary embolism have increased D.Dimer value. Therefore, the D. Dimer test is often indicated for the diagnosis of thrombotic diseases. To detect patients with hypercoagulable disease : In bedridden patients, an increased D. Dimmer test result may suggest the possibility of new thrombus formation, which is an evidence for exploration and identification. thrombosis in patients. In this case, the doctor will give the patient prophylactic anticoagulation to prevent thromboembolic complications. Monitoring of thrombotic pathology over time: When testing D. Dimer, if it is found that the normal return of D-dimer in patients with thrombotic disease, it proves that the treatment effect is progressing well, Fibrin formation is balanced again. However, if the D-dimers reappear, it is likely that the thromboembolic disease will recur and requires closer monitoring.

The way to perform the D. Dimer test is quite simple, it is necessary to prepare a test tube containing anticoagulant Citrate 3.8% to collect plasma as a specimen for analysis. Patients do not need to fast before taking blood samples for testing.
D. Dimer test results are normal if Latex test - < 500 μg/L or < 0.5 mg/L and immunoturbidity test < 250g/ml. This means that the person does not have an acute condition or disease that causes abnormal blood clots to form or break. A negative test is useful when the subject is at moderate to low risk of thrombosis.
A positive D. Dimer test result may be due to abnormally high levels of fibrin degradation products in the plasma. It can be caused by the formation and dissolution of blood clots significantly. However, the test does not indicate the exact cause or location of the clot in the body.
In fact, a positive D. Dimer test result is not always due to the formation of a blood clot. A number of other factors can cause abnormally high levels of D. Dimer in the blood such as: trauma, heart attack, infection, recent surgery, cancer or possibly an abnormal fibrin metabolism. often.
In some cases during pregnancy, Fibrin also forms and breaks more, so the amount of D. Dimer in the blood will also increase. In this case, the doctor can combine the D-dimer test with PTT, PT, Fibrinogen, platelet count test, ... in order to exclude the risk in pregnant women.
In summary, the D. Dimer test is often used as an adjunct test. Because it will give a highly sensitive result, but the specificity is not good, it is only used to rule out DVT. Depending on the specific condition, the doctor may order a D test. -dimer in combination with other tests for comprehensive disease risk assessment.
It is also important to note some risk factors affecting test results such as:
High serum rheumatoid factor titers cause false positives; Fibrinolytics increase test results; Hypersensitive D-dimer test falsely elevated or lowered due to hyperlipidemia, or turbid specimen in patients treated with mouse monoclonal antibody.

To get accurate results, people need to go to a reputable hospital with a modern equipment system for examination and a D. Dimer test by a specialist doctor. Currently, the Department of Hematology (Blood Complete Blood Test) - Vinmec International General Hospital is one of the leading prestigious addresses in the country, trusted by a large number of patients for medical examination and treatment. . Thanks to the use of modern machines and equipment to check and analyze blood, it has provided accurate information on red blood cells, white blood cells, platelets, hemoglobin,... Overall assessment of the health status of the person being tested, early detection of the disease and suggestions for timely treatment. In particular, with a space designed according to 5-star hotel standards, Vinmec guarantees to bring patients the most comfort, friendliness and peace of mind when visiting and receiving treatment at the hospital.