D-Dimer Quantitative

What is d-dimer quantitative testing and when is it used?

D-dimer quantitative testing is a blood test that measures the amount of a substance in the blood called D-dimer. It is used to help diagnose or rule out blood clotting disorders, such as deep vein thrombosis (DVT) or pulmonary embolism (PE).

D-Dimer is a substance found in the blood when the body breaks down clots. The amount of D-Dimer can indicate if this breakdown is happening and if there are blood clots in the vessels. It is especially helpful for checking venous thromboembolism in people who are at high risk.

When is the D-Dimer Quantitative Test Used?

D-dimer testing is done in clinics when doctors suspect deep venous thrombosis (DVT), pulmonary embolism (PE), or intravascular coagulation.

There are several scoring systems to find out the risk of having DVT and PE. The most well-known one is the Wells score.

A D-dimer test may not show much difference if the score is high or if there is a big chance of a problem. Anticoagulant therapy will begin regardless of the test results. Additional tests for DVT or pulmonary embolism might also be done.

What Does a Negative D-Dimer Test Mean?

If the chance of having a problem is moderate or low, a negative D-dimer test will likely rule out thromboembolism. The effect of this test on reducing the risk of blood clotting depends on how the test is performed in a clinical setting, determining the likelihood of a clot. Most D-dimer tests that give a negative result will lower the risk of thromboembolic disease to less than 1% if the initial chance is below 15-20%. A negative D-dimer test means that chest CT angiography does not need to be used to look for pulmonary embolism. A low initial chance is also helpful in ruling out PE. If you are at low or medium risk for blood clotting or thrombotic embolism, you can trust the results of the D-dimer test in the emergency room. A negative D-dimer test below a certain level shows that it is very unlikely that a clot is present. However, it is important to remember that D-dimer tests can have false positives and false negatives. A false positive means the test indicates a problem when there is not one.

If the D-dimer level is high, you will need to do more tests. These tests may include an ultrasound of the leg veins, lung scans, or CT scans to look for a clot. Depending on the situation, doctors may start anticoagulant medicine right away or wait until the tests confirm what is wrong.

In some hospitals, labs will only check D-dimer levels if the chance of a problem is low or average after filling out a form. This practice helps cut down on tests that some people don’t really need. By starting with the D-dimer test, many imaging tests can be skipped, making the process easier for patients. Since the D-dimer can show when imaging isn't needed, expert groups advise doctors to use this test first for diagnosing. If your D-dimer level is high, your doctor may ask for further tests to find out what’s wrong. Your lab results will tell you if your D-dimer level is normal, low, high, positive, or negative. D-dimer levels can also be high during pregnancy, with inflammation, cancer, trauma, after recent surgery, or due to conditions like liver disease, heart disease, or rheumatoid arthritis.

What Conditions Can Cause Elevated D-Dimer Quantitative Levels?

• D-dimer levels increase when more fibrin is created and broken down.
• This happens in several conditions, such as:
• Venous thromboembolism (VTE), which includes deep vein thrombosis and pulmonary embolism
• A heart attack (myocardial infarction) and a stroke
• Intravascular coagulation throughout the body
• A diagnosis of cancer (malignancy)
• Trauma or surgery that happened in the last 4 weeks
• Liver cirrhosis or other liver illness
• Being pregnant
• Being older than 60 years
• Sickle cell disease
• A large bruise (hematoma)
• Having fibrinolytic therapy in the last 7 days
• Severe infections, sepsis, or pneumonia
• Other forms of blood vessel disease (atherosclerotic)

The cut-off value is 0.5 µg/mL (mcg/mL) FEU. If patients have low to moderate risk, and their D-dimer result is below this value, the chance of a blood clot event is very low. However, just because the D-dimer level is normal does not mean you can ignore a thromboembolic event. A D-Dimer test measures results in milligrams per liter (mg/L) of fibrinogen equivalent units (FEU) within the reference range. The American Board of Internal Medicine says that a negative D-dimer level is below 0.50 mg/L FEU. A result above this level is considered positive. D-dimer is a protein that the body releases when blood clots dissolve. If you find D-dimer in the blood or urine, it could mean there is a blood clot somewhere. A level of 0.50 mg/L or more might show blood clots in the body. This article talks about the D-dimer test and explains what the results mean. It also covers the next steps after a positive D-dimer test.

Deep Vein Thrombosis (DVT) and Pulmonary Embolism (PE): Using D-Dimer in Testing for Two Clot-Forming and Coagulation Disorders.

D-Dimer is a protein that appears when a blood clot breaks down. Doctors use it to check for deep vein thrombosis (DVT) or pulmonary embolism (PE). Coagulation is the process that helps form blood clots, including small clots. It stops too much bleeding and involves several proteins and enzymes working together. If something goes wrong with this process, it can lead to abnormal clotting or bleeding issues. Understanding the link between D-Dimer and coagulation is key for diagnosing and treating different medical conditions related to blood clotting.

You can measure D-Dimer by testing a blood sample. It is produced during blood clotting and when a blood clot breaks down, so it can indicate a potential clotting disorder. When a blood clot starts to dissolve, D-Dimer is released and is connected to platelets in the blood and a D subunit. A high level of D-Dimer in your blood means that fibrin is forming and breaking down. Checking D-Dimer levels is helpful for diagnosing conditions like pulmonary thromboembolism (PTE) and disseminated intravascular coagulation (DIC).

When you get a cut or a wound, your body begins a process called hemostasis. This makes a clot to stop you from losing too much blood. The body creates threads of a protein called fibrin to hold the clot together. After you heal, your body breaks down the clot into smaller pieces known as fibrin degradation products, one of which is D-Dimer.

Symptoms of DVT (deep vein thrombosis) can be pain in the leg, tenderness, swelling, and color changes like redness or red streaks. For PE (pulmonary embolism), symptoms of PE might include trouble breathing, coughing, chest pain, a fast heartbeat, and a blockage in the pulmonary artery. It's very important to see a doctor if you have these symptoms. Your healthcare provider may suggest a D-dimer test if you have signs of a clotting condition, such as disseminated intravascular coagulation (DIC) or a stroke. This D-dimer test helps rule out problems that can cause DVT and PE, as well as other parts of the body that might be affected by blood clotting issues.

References

Cornell Veterinary College: Quantitative D-Dimer Assay for Animals

WebMD: Understanding the D-Dimer Test

Medical News Today: D-Dimer Test Results and Normal Ranges

Cleveland Clinic: Overview of the D-Dimer Test

NCBI: D-Dimer Test Overview from PubMed

MedlinePlus: D-Dimer Test Information

HealthDirect: D-Dimer Test - What You Need to Know