What is a D-dimer test?
A D-dimer test is a blood test that measures D-dimer, which is a protein fragment that your body makes when a blood clot dissolves in your body. D-dimer is normally undetectable or only detectable at a very low level unless your body is forming and breaking down significant blood clots.
A positive or elevated D-dimer test result may indicate that you have a blood clotting condition, but it doesn’t guarantee that you have one. A D-dimer test can't reveal what type of clotting condition you have or where the clot is located in your body.
How does blood clotting work?
Blood clotting, when functioning for its intended or normal purpose, is an important and essential process that prevents you from losing too much blood when you get injured. When a blood vessel or tissue in your body is injured and bleeds, your body kicks off a process called hemostasis to create a blood clot to limit blood loss and eventually stop the bleeding.
During the process of hemostasis, your body makes threads of a protein called fibrin, which weave together to form a fibrin net. The net, in addition to a type of cell called a platelet, helps anchor the forming blood clot in place until the injury heals. These blood clots may appear as scabs on your skin or bruises under your skin.
Once your injury has healed and your body no longer needs the blood clot, your body makes an enzyme called plasmin to break down the clot into small fragments in order to remove it. The fragments are known as fibrin degradation products, or fibrin split-products. D-dimer is one of those fibrin degradation products.
If you have a blood clotting condition, blood clots can form when you don’t have an injury, and/or they don’t break down when they should. In other words, your body’s blood clotting process isn’t working as it should. Blood clotting conditions can be serious and life-threatening.
Having a high D-dimer level in your blood can be a sign of a blood clotting disorder since the level of D-dimer can rise greatly when there’s significant formation and breakdown of blood clots in your body.
What is a D-dimer test used for?
Healthcare providers most often use D-dimer tests to help determine if someone has a blood clotting condition, which include:
- Deep vein thrombosis (DVT or venous thrombosis): Deep vein thrombosis is a blood clot that develops in a vein deep in your body. The clot may partially or completely block blood flow through the vein. Most DVTs happen in your lower leg, thigh or pelvis, but they can also occur in other parts of your body including your arm, brain, intestines, liver or kidney.
- Pulmonary embolism (PE): A pulmonary embolism is a blood clot in your lung that happens when a clot in another part of your body (often your leg or arm) flows through your bloodstream and becomes lodged in the blood vessels of your lung.
- Disseminated intravascular coagulation (DIC): DIC causes too many blood clots to form in your body, which can cause organ damage and other serious complications. In addition to using a D-dimer test to help diagnose DIC, healthcare providers use the test to help monitor the effectiveness of DIC treatment.
- Stroke: A stroke, or "brain attack," happens when a blood vessel in your brain becomes blocked or bursts.
Why do I need a D-dimer test?
Your healthcare provider may have you undergo a D-dimer test if you’re having symptoms of a blood clotting condition, which include:
- Deep vein thrombosis (DVT).
- Pulmonary embolism (PE).
- Disseminated intravascular coagulation (DIC).
Providers usually perform D-dimer tests in an emergency room or other hospital setting.
Deep vein thrombosis (DVT)
A DVT usually forms in one of your legs or arms. Not everyone with a DVT will have symptoms, but symptoms can include:
- Swelling of your leg or arm, which sometimes happens suddenly.
- Pain or tenderness in your leg, which may only happen when standing or walking.
- Warmth in the area of your leg or arm that’s swollen or hurts.
- Skin that is red or discolored.
- Having veins near the surface of your skin that are larger than normal.
If you’re experiencing signs and symptoms of DVT and aren't currently in a healthcare setting, call your healthcare provider as soon as possible.
Pulmonary embolism (PE)
Symptoms of a pulmonary embolism include:
- Sudden shortness of breath (dyspnea) or fast breathing.
- Sharp chest pain that often happens when you cough or move.
- Pain in your back.
- Coughing (sometimes with bloody spit or phlegm).
- Sweating more than you usually do.
- Fast heart rate (tachycardia).
- Feeling dizzy or fainting.
If you have symptoms of a pulmonary embolism, call 911 or get to the nearest emergency room as soon as possible.
Disseminated intravascular coagulation (DIC)
Symptoms of DIC include:
- Bleeding gums.
- Nausea and/or vomiting.
- Severe muscle pain and abdominal pain.
- Peeing less than you normally do.
If you’ve already been diagnosed with DIC, your healthcare provider may have you undergo D-dimer tests regularly to make sure your treatment is working well.
Symptoms of a stroke include:
- Sudden numbness or weakness in your face, arm or leg, especially on one side of your body.
- Sudden confusion, trouble speaking or difficulty comprehending what someone is saying.
- Sudden difficulty seeing in one or both of your eyes.
- Sudden trouble walking.
- Sudden dizziness, loss of balance or lack of coordination.
- Sudden severe headache with no known cause.
If you or someone else is experiencing these signs and symptoms of a stroke, call 911 or get to the nearest hospital as soon as possible.
Who performs a D-dimer test?
A healthcare provider known as a phlebotomist usually performs blood draws, including those for a D-dimer test, but any healthcare provider trained in drawing blood can perform this task. Your provider then sends the samples to a lab where a medical laboratory scientist prepares the samples and performs the tests on machines known as analyzers.
How do I prepare for a D-dimer test?
You don't need to do anything special to prepare for a D-dimer test.
What should I expect during my D-dimer test?
A D-dimer test is a blood test. You can expect to experience the following during a blood test, or blood draw:
- You’ll sit in a chair or lie on a medical bed, and a healthcare provider will check your arms for an easily accessible vein. This is usually in the inner part of your arm on the other side of your elbow.
- Once they’ve located a vein, they’ll clean and disinfect the area.
- They’ll then insert a small needle into your vein to take a blood sample. This may feel like a small pinch.
- After they insert the needle, a small amount of blood will collect in a test tube.
- Once they have enough blood to test, they’ll remove the needle and hold a cotton ball or gauze on the site to stop the bleeding.
- They’ll place a bandage over the site, and you’ll be finished.
The entire process usually takes less than five minutes.
What should I expect after my D-dimer test?
After a healthcare provider has collected your blood sample, they’ll send it to a laboratory for testing. Once the test results are back, your healthcare provider will share the results with you.
What are the risks of a D-dimer test?
Blood tests are a very common and essential part of medical testing. There’s very little risk to having blood tests. You may have slight tenderness or a bruise at the site of the blood draw, but this usually resolves quickly.
Results and Follow-Up
What do the results of a D-dimer test mean?
Blood test reports, including D-dimer test reports, usually provide the following information:
- The name of the blood test or what was measured in your blood.
- The number or measurement of your blood test result.
- The normal measurement range for that test.
- Information that indicates if your result is normal or abnormal, high or low or positive or negative.
What is a normal D-dimer test result?
There are several different methods for testing the level of D-dimer in your blood, so there’s no one universal “normal” range. Your lab results will provide information indicating if your D-dimer level is normal, low or high or positive or negative.
If your lab results reveal that you have low, negative or normal D-dimer levels in your blood, it means you most likely don’t have a clotting disorder.
If you’ve been diagnosed with disseminated intravascular coagulation (DIC) and are undergoing treatment, a normal or low level of D-dimer in your blood most likely means that your treatment is working well.
What does a high D-dimer test result mean?
If your results reveal that you have higher-than-normal levels of D-dimer in your blood, it may mean that you have a blood clotting condition. A D-dimer test can't determine the type of blood clotting condition you may have or where the blood clot(s) is in your body.
If you’ve been diagnosed with disseminated intravascular coagulation (DIC) and are undergoing treatment, a high level of D-dimer in your blood most likely means that your treatment isn’t working well.
It’s possible to have high D-dimer levels without having a blood clotting condition. Other conditions and situations that can cause higher-than-normal levels of D-dimer include:
- Heart disease.
- Recent surgery.
D-dimer levels also tend to rise in elderly people, and false-positive results may occur if you have rheumatoid arthritis.
If your results show abnormal D-dimer levels, your healthcare provider will likely have you undergo additional blood tests and/or imaging tests to determine a diagnosis.
When should I know the results of my D-dimer test?
In most cases, healthcare providers order D-dimer tests in emergency situations since blood clots can be life-threatening. If this scenario applies to you, your provider will likely have the results back within hours.
If you’ve had a D-dimer test to monitor the effectiveness of your treatment plan for a blood clotting condition, you’ll likely have the results back within one to two business days.
What are the next steps?
If your D-dimer test results were abnormal, your healthcare provider may have you undergo one or more imaging tests to find out if you have a blood clotting condition and where the blood clot(s) may be. Imaging tests include:
- Doppler ultrasound: This imaging test uses sound waves to create images of your veins.
- Computed tomography (CT) angiography: For this imaging test, a healthcare provider injects a special dye into one of your veins. This helps your blood vessels show up on a special type of X-ray machine.
- Lung ventilation-perfusion (V/Q) scan: A lung VQ scan is an imaging test that uses a ventilation (V) scan to measure airflow in your lungs and a perfusion (Q) scan to see where blood flows in your lungs. Both tests use small and safe amounts of radioactive substances to help a scanning machine see how well air and blood move through your lungs.
When should I call my doctor?
If you’re experiencing symptoms of stroke or pulmonary embolism, call 911 or get to the nearest emergency room as soon as possible.
If you’re experiencing symptoms of deep vein thrombosis, call your healthcare provider as soon as possible.
Frequently Asked Questions
What are the risk factors for developing blood clots?
Risk factors for developing inappropriate or abnormal blood clots include:
- Having major surgery or experiencing trauma.
- Prolonged immobility, which can include sitting for long trips or prolonged bed rest.
- Taking birth control pills or hormone replacement therapy.
- Pregnancy or recent childbirth.
- Having a family history of blood clots, or a specific condition, such as Factor V Leiden disease, antiphospholipid syndrome or polycythemia vera.
- Having a certain kind of cancer.
- Having coronavirus disease 2019 (COVID-19).
- Having obesity.
A note from Cleveland Clinic
Seeing an abnormal test result can be stressful. Know that having a high D-dimer test result doesn’t necessarily mean you have a blood clotting condition. If your results show you have an elevated level of D-dimer, your healthcare provider will likely have you undergo further tests to determine a diagnosis. Don’t be afraid to ask your provider questions. They’re there to help you.
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