D-dimer: Values, When It Is Raised and What the Result Means
D-dimer is the test most often ordered when a doctor wants to rule out a clot: in the veins of the leg, in the lungs or after surgery. What is rarely explained is that D-dimer is a test that rules out well and confirms poorly. A low result in someone with a low probability practically rules out thrombosis, while a raised result most often does not mean a clot, because D-dimer also rises with infection, pregnancy, inflammation, after surgery and with age. This article covers the normal values, how a raised result is read and which examination comes next.
What D-dimer is
When a clot forms in the body, the body starts breaking it down at the same time. D-dimer is a fragment of fibrin left behind by that breakdown. Its level in the blood therefore says that fibrin is being formed and broken down somewhere in the body, and besides thrombosis that happens with every stronger inflammation, injury, operation, tumor, in pregnancy and in older people.
Normal D-dimer values
| Situation | Cut-off | Note |
|---|---|---|
| Adults, standard cut-off | below 500 ng/mL FEU (0.5 mg/L FEU; in some laboratories 0.5 µg/mL) | If the laboratory reports in DDU units, the cut-off is around 250 ng/mL. Always check the unit on your report. |
| Over the age of 50 | age × 10 ng/mL FEU | An adjusted cut-off: for a person of 70 that is 700 ng/mL. D-dimer rises naturally with age. |
| Pregnancy, 1st trimester | up to about 750 ng/mL | A physiological rise; there is no single cut-off. |
| Pregnancy, 2nd trimester | up to about 1.500 ng/mL | The result is read alongside symptoms, not on its own. |
| Pregnancy, 3rd trimester | up to about 2.500 ng/mL, sometimes higher | Close to delivery D-dimer is almost always “raised” by the standard cut-off. |
A raised D-dimer: what it means and what it does not
A raised D-dimer on its own is not a diagnosis of thrombosis. Alongside deep vein thrombosis and pulmonary embolism, the same result is produced by:
- infections, including pneumonia and a heavy cold, and any active inflammation (a high CRP usually comes with a high D-dimer);
- pregnancy and the first weeks after delivery;
- surgery, injury, a large hematoma, a fracture;
- age over 60 and chronic disease of the kidneys, liver and heart;
- malignant disease and its treatment;
- estrogen therapy and hormonal contraception;
- varicose veins with inflammation of the superficial veins.
That is why a doctor first estimates the probability of thrombosis from the symptoms: swelling of one leg, calf pain, warmth and redness on one side, recent immobility, a flight, a cast, surgery, pregnancy, earlier thrombosis in the family. With a low probability and a normal D-dimer, no further investigation is needed. With a raised D-dimer, or with a high probability whatever the result, the next step is imaging, not repeating the test.
The next examination: a venous Doppler
When thrombosis in the leg is suspected, the examination of choice is a color Doppler of the leg veins: an ultrasound scan that shows directly whether the vein is open and whether there is a clot in it. It is painless, takes 15 to 20 minutes and needs no preparation. When pulmonary embolism is suspected, with chest pain, difficulty breathing or coughing up blood, you do not go for a Doppler but to emergency care, because a CT scan of the lungs is what is needed.
When thrombosis is confirmed or keeps recurring without a clear reason, a hematologist investigates the tendency to clot (thrombophilia), while a vascular surgeon leads the treatment and assesses the veins. For chronic problems with the leg veins, swelling and varicose veins, an appointment with a vascular surgeon including a Doppler is the examination that gives an answer without unnecessary tests.
What an appointment at Miren Medic looks like
With a raised D-dimer and symptoms in the leg, the Miren Medic clinic carries out in a single visit an appointment with a vascular surgeon (Dr Anica Ilić, specialist in vascular surgery, or Dr Radivoje Zoranović with a Doppler) and a color Doppler of the veins, performed by the radiologists Dr Oliver Radmili, Dr Uroš Miladinović and Dr Bojana Krća. The tests, including D-dimer, CRP and the blood count, are run in the clinic laboratory. Thrombophilia testing is handled by Assist. Prof. Dr Danijela Leković, hematologist. All of it without a referral.
Prices
| Service | Price |
|---|---|
| Doppler of the leg blood vessels (Dr Oliver Radmili) | 7.000 RSD |
| Doppler of the blood vessels of the arm/leg/head (Dr Uroš Miladinović) | 6.000 RSD |
| Vascular surgery appointment (Dr Anica Ilić) | 8.000 RSD |
| Surgical appointment + Doppler of the blood vessels (Dr Radivoje Zoranović) | 10.000 RSD |
| Hematology appointment (Assist. Prof. Dr Danijela Leković) | 12.000 RSD |
Frequently asked questions
What are normal D-dimer values?
Below 500 ng/mL FEU (0.5 mg/L) in adults. After the age of 50 the cut-off is adjusted by the formula age × 10, so for a person of 70 it is 700 ng/mL. In pregnancy D-dimer rises physiologically by trimester, so the standard cut-off does not apply there.
What does a raised D-dimer mean?
That fibrin is being formed and broken down somewhere in the body. That happens with thrombosis, but also with infection, inflammation, after surgery, in pregnancy, with tumors and with age. A raised result is not a diagnosis; it is a reason to assess the symptoms and, if needed, to do a venous Doppler.
Does a raised D-dimer mean I have a clot?
Most often no. D-dimer is a test that rules thrombosis out well when it is low, but confirms it poorly when it is high, because it rises for many other reasons. A clot is confirmed or ruled out by a venous Doppler, and when pulmonary embolism is suspected by a CT scan.
What are D-dimer values in pregnancy?
They rise through the pregnancy: roughly up to 750 ng/mL in the first, up to 1.500 in the second and up to 2.500 ng/mL or more in the third trimester. In pregnancy the result is therefore not read against the standard cut-off but alongside the symptoms and the doctor's assessment.
How is a raised D-dimer treated?
The result is not what gets treated, the cause is. If thrombosis is confirmed, the treatment is led by a vascular surgeon or a hematologist with anticoagulant therapy. If the cause is not a clot, D-dimer falls by itself once the infection, the inflammation or the recovery after surgery has passed.
When is a raised D-dimer an emergency?
When it comes with sudden chest pain, difficulty breathing, a racing pulse, coughing up blood or fainting: those are signs of a possible pulmonary embolism and go to emergency care. Swelling and pain in one leg call for a venous Doppler the same day or the next.
Book an appointment
If your D-dimer is raised or you have swelling and pain in the leg, book an appointment with a vascular surgeon including a venous Doppler at the Miren Medic clinic. The examination, the ultrasound and the tests come in a single visit, without a referral.
