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Diagnostic Tests 2023

DíD-number: what é, what it's for and why it's á increased

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DíD-number: what é, what it's for and why it's á increased
DíD-number: what é, what it's for and why it's á increased

D-dimer is a biological marker that is present in the blood when there is degradation of fibrin, a protein that is involved in clot formation. Thus, when there are changes in the clotting process, it is expected that there will be a greater amount of circulating D-dimer.

The D-dimer test is recommended by the doctor to assess the risk of thrombosis and pulmonary thromboembolism, being mainly indicated after surgery, after major trauma, such as accidents, for example, and during pregnancy.

The reference value of D-dimer in the blood is up to 0.500 ┬Ád/mL or 500 ng/mL, and it is important to investigate the cause in case of increased values, which can be done through other tests of blood such as CBC, liver markers and C-reactive protein, for example.


What is it for

D-dimer measurement is usually indicated to confirm or rule out the possibility of deep vein thrombosis or pulmonary thromboembolism, as this marker is increased in these situations.

However, as it is a coagulation marker, D-dimer can also be requested to assess the functioning of the clotting process. Understand better how clotting happens.

Thus, in addition to ruling out the occurrence of deep vein thrombosis and pulmonary thromboembolism, the D-dimer dosage can also be useful in the investigation of situations that can interfere with clotting, such as heart problems and inflammation, for example.

Increased D-Dimer Result

Increased D-dimer levels are mainly related to increased risk of deep vein thrombosis (DVT) and/or pulmonary thromboembolism (PTE).

However, other situations that can lead to D-dimer increase are:

  • Disseminated intravascular coagulation;
  • After major surgery;
  • Big trauma;
  • During pregnancy;
  • Heart, kidney or liver disease;
  • Inflammations;
  • Use of anticoagulants;
  • Some types of cancer;
  • COVID-19 in some cases.

In addition to the D-dimer assessment, it is important that other tests are performed to help identify the cause of the increase in this marker. Thus, according to the person's he alth history and the presence of symptoms, the doctor may recommend a blood count, tests to assess liver, kidney and heart function and lactate dehydrogenase and C-reactive protein dosage.

Other tests that can be ordered together with the D-dimer are prothrombin time, thrombin time, bleeding time and partial thromboplastin time, which are tests that are part of the coagulogram and allow to assess whether the process of clotting is happening normally. Learn more about coagulogram tests.

D-Dimer and COVID-19

The increase in D-dimer is a common laboratory finding in cases of COVID-19, because in the body's attempt to fight the virus responsible for the disease, a large amount of cytokines is released, which causes damage to the blood vessels and activates the clotting cascade. Thus, there is activation of a large amount of fibrin and, consequently, of the pathway responsible for degrading this protein, increasing circulating levels of D-dimer.

In this way, the increase in the levels of this marker in the blood may be indicative of infection and, depending on the values, may be suggestive of greater severity of COVID-19 and the risk of intravascular coagulation and thrombosis, being in these cases necessary internment. However, it is also important that fibrin levels, platelet count and prothrombin time and the symptoms presented by the person are evaluated. See more about COVID-19.

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