D-dimer: what it is, what it is for, values ​​and why it is high

D-dimer is a biological marker that indicates changes in the coagulation process. This happens because this marker is released into the blood when there is degradation of fibrin, a protein that is involved in the formation of clots.

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

When the D-dimer value is high, it is important to investigate the cause, which can be done through other blood tests such as blood count, liver markers and C-reactive protein, for example.

D-dimer reference value

The reference value for D-dimer in blood is up to 0.500 µd/mL or 500 ng/mL.

What is it for

D-dimer measurement is normally 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 evaluate the functioning of the coagulation process. Understand better how clotting happens.

Therefore, in addition to serving to rule out the occurrence of deep vein thrombosis and pulmonary thromboembolism, D-dimer measurement can also be useful in investigating situations that can interfere with coagulation, such as heart problems and inflammation, for example.

What does high D-dimer mean?

A high D-dimer value normally indicates that there is an increased risk of developing deep vein thrombosis (DVT) and/or pulmonary thromboembolism (PTE).

However, there are other situations that can lead to an increase in the D-dimer value, such as:

• Disseminated intravascular coagulation;
• After major surgeries;
• Major traumas;
• During the pregnancy;
• Heart, kidney or liver diseases;
• Inflammations;
• Use of anticoagulants;
• Some types of cancer;
• COVID-19, in some cases.

In addition to evaluating the D-dimer, it is important to carry out other tests that help identify the cause of the increase in this marker. Therefore, according to the person’s health history and the presence of symptoms, the doctor may recommend a blood count, tests to evaluate the function of the liver, kidneys and heart and measurement of lactate dehydrogenase and C-reactive protein.

Other tests that can be requested 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 that allow assessing whether the clotting process is happening normally. . Find out more about coagulogram exams.

Dimer-D and COVID-1

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 coagulation cascade. In this way, there is activation of a large amount of fibrin and, consequently, the pathway responsible for degrading this protein, increasing circulating levels of D-dimer.

Therefore, increased 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, requiring hospitalization in these cases. However, it is also important that fibrin levels, number of platelets and prothrombin time and the symptoms presented by the person are evaluated. See more about COVID-19.