Table of ContentsView AllTable of ContentsWhat Is The Test?What Is It Used For?Why Do I Need It?What to ExpectFAQ
Table of ContentsView All
View All
Table of Contents
What Is The Test?
What Is It Used For?
Why Do I Need It?
What to Expect
FAQ
The D-dimer test is a blood test doctors can use to rule out a severe blood clot. A normal result would be less than 500 nanograms per milliliter (ng/mL) and anything above that is considered a positive test.It’s useful if your doctor suspects you have a blood clot in your lung or deep within a vein of your leg or pelvis.
These clots can be fatal. Getting prompt treatment increases your chances of surviving and avoiding other medical problems.
This article discusses the D-dimer test, how doctors use it, and its limitations. It also explains the link between COVID-19 and elevated D-dimer levels.
Verywell / Brianna Gilmartin
What Is a D-Dimer Test?
D-dimer is a substance involved in the body’s healing process. When you get an injury that causes you to bleed, your body uses proteins to clump up your blood. The clot that forms plugs the damaged vessel.
Once the bleeding stops, your body sends out other proteins to slowly break down the clot. Afterward, you end up with fragments of D-dimer in your blood.
How Blood Clotting WorksA blood clot forms through a process called hemostasis as a result of injury to a blood vessel or tissue. The semi-solid mass of blood cells that form control the bleeding and eventually bring it to a stop. While blood clots can act as a first line of defense against blood loss, they can also develop as a result of certain medical conditions and cause life-threatening symptoms.
How Blood Clotting Works
A blood clot forms through a process called hemostasis as a result of injury to a blood vessel or tissue. The semi-solid mass of blood cells that form control the bleeding and eventually bring it to a stop. While blood clots can act as a first line of defense against blood loss, they can also develop as a result of certain medical conditions and cause life-threatening symptoms.
These protein fragments usually dissolve over time. However, if a clot doesn’t break up or another one forms, you’ll have high levels of D-dimer in your blood.
The D-Dimer test is a blood test that can measure the amount of these fragments in your blood.
Can COVID Cause High D-Dimer Results?Yes, COVID-19 can cause elevated D-dimer levels. COVID is associated with an increased risk of blood clots. The D-dimer test is used to identify blood clots. One study found 15% of patients had elevated D-dimer levels three months after having a serious case of COVID.
Can COVID Cause High D-Dimer Results?
Yes, COVID-19 can cause elevated D-dimer levels. COVID is associated with an increased risk of blood clots. The D-dimer test is used to identify blood clots. One study found 15% of patients had elevated D-dimer levels three months after having a serious case of COVID.
What Are Blood Clots?
Anyone can get a blood clot. Doctors usually order a D-dimer test to rule out two dangerous types of blood clots.Deep vein thrombosis or DVT: a blood clot that forms deep within a veinPulmonary embolism or PE: a blood clot that travels from other parts of the body and ends up in an artery of your lungs
Anyone can get a blood clot. Doctors usually order a D-dimer test to rule out two dangerous types of blood clots.
What Is a D-Dimer Test Used For?
A D-Dimer test is used to warn of the possibility of a severe blood clot and diagnose certain conditions before they become life-threatening.
As many as 100,000 deaths occur each year in the U.S. due to deep vein thrombosis, a blood clot deep within a vein, and pulmonary embolism, a blood clot in your lung.The symptoms you may have include:
Diagnosing these conditions and getting prompt treatment increases your chances of surviving PE and DVT.It also helps you avoid other medical problems that can hurt your quality of life.
Ruling out DVT and PE is the main reason doctors order D-dimer tests. However, the test can help doctors evaluate and manage other severe conditions that involve blood clots as well. These include:
Why Do I Need the D-Dimer Test?
Diagnosing these conditions can be tricky. One study found that nearly 70% of people seen in outpatient clinics and emergency rooms with symptoms of a DVT didn’t have one.
Doctors used to have to send all blood samples to a central lab for analysis. This caused delays and meant the test couldn’t be used for emergencies. So doctors were forced to send patients for expensive imaging tests instead.
The D-dimer test is a simple and relatively quick way to diagnose what could be a rapidly worsening and life-threatening condition. Healthcare providers can order D-dimer tests in emergency situations and have the results back within 24 hours.
In recent years, the Food and Drug Administration has approved several rapid D-dimer tests. These tests provide doctors with a fast, inexpensive way to rule out DVT or PE.
Before the Test
There’s no special preparation before taking the D-Dimer test. You do not have to fast or do it at a certain time of day. That being said, check with your healthcare provider if there are any special instructions they want you to be aware of.
During the Test
The D-Dimer testing process is simple. A blood sample is taken from the vein, usually in the arm, using a small needle. For most people, having blood taken feels like a pinch or prick when the needle is inserted into your arm. If your veins are difficult to find, it may be more challenging for the phlebotomist to get a sample of your blood and analyze it. Your arm may feel a little sore at the site of the blood draw later in the day or the next day.
After the Test
Most people will feel normal as soon as the test is complete. You may have mild soreness in the arm muscle or slight bruising. Typically, results will be ready in a day or two.
What Do the Results Mean?
Results can vary depending on the test your doctor used and the design.Doctors need to know the ranges of normal and abnormal levels for the test they’re using. The reference range can vary from laboratory to laboratory, but in general, a normal D-dimer range is 220 to 500 ng/mL.
If your results are in the lower range, your doctor can safely rule out a blood clot.If your results come back abnormal or high, you’ll likely need more tests. The D-dimer test cannot be the sole basis to diagnose DVT or PE.
Patients with a low risk of blood clots and whose D-dimer levels are in the lower to middle range likely don’t have a pulmonary embolism. Studies show the D-dimer test is comparable to ultrasonography or CT angiography in ruling out PE.
Nearly all patients with DVT have elevated D-dimer levels.This makes the test beneficial in ruling out the condition for patients with levels in the lower to middle range. The test is also helpful if your symptoms aren’t that clear. If your levels are high, your doctor will order more tests.
What Does a High D-Dimer Mean?
High or abnormal results suggest you may have a blood clot, but it does not definitively mean a clot is present. There could be other reasons why your results are high, and your doctor will order further testing to determine the cause.
Also, many people who’ve had a recent PE will still have elevated D-dimer levels. So the test isn’t helpful for them.
In addition to PE, many diseases, treatments, and lifestyle factors can raise your D-dimer levels. Thus, it’s essential to thoroughly answer your doctor’s questions about your medical history. People with blood clots often have one or more of the same risk factors. They include:
Medical conditions and treatments:
Other risk factors:
Doctors may order other tests to make sure you don’t have PE or DVT:
How Deep Vein Thrombosis Is Diagnosed
Summary
Doctors may order a D-dimer test if they suspect you might have a dangerous blood clot. The test helps doctors rule out two conditions that can be fatal: deep vein thrombosis, a blood clot in a vein, and pulmonary embolism, a blood clot in the lung. The test can also help diagnose other conditions that cause blood clots such as stroke and coronary artery disease.
A negative test result means you probably don’t have a blood clot. Usually, you won’t need any further tests. However, if your results come back high, that doesn’t necessarily mean you have a clot. The test isn’t definitive. Your doctor will likely order other tests.
Frequently Asked Questions
Abnormal results on a D-dimer test warrant further testing. This can include Doppler ultrasound, computed tomography (CT) angiography, or lung ventilation-perfusion (V/Q) scan. Treatment depends on the cause of high D-dimer levels but typically includes statins or blood thinning medications.
However, if your D-dimer levels are high, speak to your healthcare provider before trying natural remedies. A blood clot can be serious and should not be ignored.
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