High D-dimer: what it means and what to do

First: if you have a swollen, painful leg, sudden breathlessness, chest pain or you are coughing up blood, call 112 or go to the emergency department. If you feel well, a high D-dimer often comes from age, pregnancy, recent surgery or an infection. Your doctor decides whether more tests are needed.

What a high D-dimer means

Your body forms and dissolves small clots every day. When it dissolves more of them, more fragments of fibrin reach your blood: the D-dimer rises.

A clot raises it, but so do many harmless things. That is why a high D-dimer alone does not make a diagnosis: it tells your doctor a closer look may be needed.

A high D-dimer is a signal to understand, not a verdict. How you feel and what your doctor finds count more.

What causes a high D-dimer

Harmless causes are the most common. A clot is the one to rule out.

• Age: It rises on its own over the years. From 50, the cut-off is adjusted for age.
• Pregnancy and birth: It rises during pregnancy and after the birth. A high value alone says little.
• Surgery, injuries, fractures: It stays high for a few weeks after an operation or an injury.
• Infections and inflammation: Pneumonia, COVID, flu or an inflammatory disease raise it.
• Deep vein thrombosis or pulmonary embolism: These are the causes your doctor wants to rule out. They usually cause symptoms.
• Other causes: Cancer, liver or kidney disease, atrial fibrillation, bleeding. Your doctor weighs them with other tests.

Symptoms not to ignore

A high D-dimer on its own causes no symptoms. The symptoms of a clot are what count. If you have one, call 112 or go to the emergency department:

• A leg, usually a calf, that is swollen, warm, red and painful
• Breathlessness that comes on suddenly
• Chest pain that gets worse when you breathe
• Coughing up blood, a very fast heartbeat or fainting

Do not wait for a test result if you have these symptoms: the emergency department does everything that is needed.

High D-dimer, age and pregnancy

Over the years, D-dimer rises even in people who are well. That is why, from age 50, many doctors use a cut-off that grows with age: your age times 10, in ng/mL FEU. This avoids many unnecessary tests without missing clots.

In pregnancy, D-dimer rises month by month. A high value is common and, on its own, says little.

If you are pregnant or have recently given birth and have a swollen leg or breathlessness, call 112 or go to the emergency department. For everything else, talk to your gynaecologist.

Which tests to read alongside it

Your doctor uses them to find where it comes from.

What to do with a high D-dimer

It depends on how you feel:

• If you have symptoms of a clot, call 112 or go to the emergency department.
• If you have no symptoms, take the report to your doctor in the next few days. They weigh your risk and decide whether an ultrasound or other tests are needed.
• If you have recently had surgery, an infection or a baby, tell them: it often explains the value.
• Do not take aspirin or anticoagulants on your own. If you already take them, do not stop them or change the dose without your doctor.

Do not repeat the test yourself several times to see if it falls: it does not change the decision, which is your doctor’s to make.

High D-dimer: when to worry

How you feel counts more than the number:

• You have a swollen, painful leg, sudden breathlessness, chest pain, you are coughing up blood or you faint: call 112 or go to the emergency department.
• You have pain in a calf after surgery, a long journey, a plaster cast or giving birth: see your doctor the same day.
• You have a high D-dimer from a check-up and feel well: talk to your doctor in the next few days.
• You have had a clot before, or clots at a young age run in your family: tell your doctor.

Frequently asked questions

High D-dimer: when should I worry? When there are symptoms: a swollen, painful leg, sudden breathlessness, chest pain. Then call 112 or go to the emergency department. Without symptoms, talk to your doctor.

Can you have a high D-dimer without a clot? Yes, often. Age, pregnancy, surgery, an infection or inflammation raise it. That is why your doctor also looks at symptoms and risk.

What is the D-dimer cut-off by age? From 50, many doctors use your age times 10 as the cut-off, in ng/mL FEU: 600 at 60, 800 at 80. Under 50, the most common cut-off is 500.

High D-dimer in pregnancy: is it normal? Yes, it rises on its own in pregnancy and a high value is common. If you have a swollen leg or breathlessness, call 112 or go to the emergency department. Otherwise, talk to your gynaecologist.

How do you bring D-dimer down? It cannot be lowered directly: it falls when the cause goes away. If there is a clot, your doctor treats it with the right medicines. Do not take anticoagulants on your own.

Can a high D-dimer be cancer? Some cancers raise it, but it is an uncommon cause. Usually there are simpler reasons. If the value has no explanation, your doctor decides what to look at.

Sources

• Konstantinides and colleagues, 2019 ESC guidelines for the diagnosis and management of acute pulmonary embolism. European Heart Journal, 2020. PMID 31504429
• Righini and colleagues, age-adjusted D-dimer cutoff levels to rule out pulmonary embolism: the ADJUST-PE study. JAMA, 2014. PMID 24643601
• Wells and colleagues, evaluation of D-dimer in the diagnosis of suspected deep-vein thrombosis. New England Journal of Medicine, 2003. PMID 14507948