What Is a D-Dimer Test? Normal Range and Elevated Levels - GoodRx (2024)

In the U.S., blood clots affect up to 900,000 people each year and can happen to anyone. If you’re at risk for a blood clot, you may have heard of a D-dimer test. It’s a blood test that healthcare providers sometimes use to screen people for blood clot risk.

The D-dimer test can help diagnose a deep vein thrombosis (DVT) or pulmonary embolism (PE). But the test can have some pitfalls. So we’ll explain what you need to know about this test and how to understand your results.

What is a D-dimer test?

A D-dimer test detects how much D-dimer is circulating in your blood. D-dimer is a substance that comes from the breakdown of blood clots in the body.

High D-dimer levels sometimes occur in conditions where blood clots are more likely to happen — such as pregnancy or cancer. People with blood clots in the arms or legs (DVT) or in the lungs (PE) can also have elevated levels.

But people with blood clots can still have a normal D-dimer level. And people with high D-dimer levels don’t necessarily have a clot. So a D-dimer test can’t diagnose a blood clot by itself. But it can help figure out if you need more testing for a blood clot. We’ll go into this in more detail below.

What is a normal D-dimer range?

The normal range for a D-dimer depends on two things:

1. The specific test that is used

2. Individual characteristics of the person who is tested

D-dimer tests aren’t standardized or all done the same way. This means they each have their own normal range. The results you get from your lab should tell you what is normal for your specific test.

There are also factors that can change what is normal for you. For example, D-dimer levels naturally increase as you get older. So a higher D-dimer result may be normal in an older adult (over age 50). D-dimer levels also naturally increase in normal pregnancy, and the normal-range cutoffs increase from trimester to trimester.

What causes an elevated D-dimer level?

Some people with an elevated D-dimer level don’t have a blood clot. This may be because another medical condition is elevating the D-dimer level. Other conditions that can raise the D-dimer level include:

• Older age

• Pregnancy

• Cancer

• Recent surgery

• Liver disease

• Kidney disease

• Infection

• Chronic inflammation

It’s challenging to use the D-dimer test to diagnose a blood clot when another condition causes the D-dimer to be high.

Can COVID cause an elevated D-dimer level?

Yes, COVID-19 can elevate a D-dimer level and also increase the risk of blood clots. This risk applies mainly to people who are hospitalized with severe cases of COVID-19. People with COVID-19 who don’t need hospitalization can also get blood clots, but they’re likely at lower risk — especially if they don’t have other medical problems.

Healthcare teams can use D-dimer tests in people hospitalized with COVID-19 to identify those who may be at higher risk for blood clots. In some cases, they may prescribe heparin, a blood thinner, to prevent and treat blood clots.

D-dimer testing and blood thinners aren’t recommended routinely for people with COVID-19 who aren’t hospitalized. If you think you may have a blood clot after being diagnosed with COVID-19, talk to your healthcare provider to see if you need additional testing.

Can you have an elevated D-dimer level but no clots?

Yes, you can have an elevated D-dimer level but no blood clots. This is why it’s important to consider whether another condition is causing the high D-dimer. On the other hand, it’s also possible to have a blood clot and a normal D-dimer level.

But the D-dimer test can be a helpful first step in the blood-clot workup.

What happens if your D-dimer level is high?

A high D-dimer level increases the likelihood that you have a blood clot. But it doesn’t tell you this for sure or where in the body it may be. A D-dimer test alone can’t diagnose a blood clot with certainty. More testing is needed.

Additional testing for blood clots uses imaging or a radiology test. If a provider suspects a blood clot in the arm or leg (DVT), they’ll run an ultrasound to look for the clot. To look for a blood clot in the lungs (PE), the preferred test is often a CT scan of the chest using intravenous (IV) contrast dye.

If more testing is needed to diagnose a blood clot, you may wonder why the D-dimer test is used at all. Here’s the main reason: The D-dimer test is faster and easier to do than radiology testing. And when you’re at low risk for a blood clot and your D-dimer test is normal, this can rule out a blood clot and spare you the time and expense of more testing. It also reduces radiation exposure that comes from a CT scan of the chest. This can be particularly important in certain groups of people, such as those who are pregnant.

But if your healthcare provider thinks there’s a good chance you have a blood clot — even if your D-dimer is normal — you’ll need to undergo more testing to know for sure.

How do you treat a high D-dimer level?

Whether a high D-dimer level needs treatment depends on the cause. If the cause of a high D-dimer level is age, pregnancy, or another medical condition, the D-dimer doesn’t need treatment.

But if the cause of a high D-dimer level is a blood clot, you may need treatment with an anticoagulant medication, or blood thinner.