What Is a D-Dimer?

Reviewed on 9/15/2022

A person's arm getting poked by a needle for a blood test
A D-dimer test is used to diagnose blood clotting problems such as deep vein thrombosis (DVT), pulmonary embolism (PE), disseminated intravascular coagulation (DIC), and stroke.

A D-dimer test is a blood test used to check for blood clotting problems.

Blood clots can cause health problems, such as:

A D-dimer test may be indicated in people who have symptoms of blood clots, such as:

  • Swelling, pain, warmth, tenderness to the touch, and redness in the affected area
  • Swelling in the leg or arm
  • Changes in skin color of a leg or arm
  • Cramp-like feeling
  • Sharp chest pain
  • Fast heart rate
  • Palpitations
  • Numbness or weakness on one side of the body
  • Abrupt change in mental status
  • Bleeding gums
  • Nausea and vomiting
  • Severe stomach pain
  • Severe muscle pain 
  • Decreased urine 
  • Seizures

If a blood clot breaks off and travels to the lung, this is called a pulmonary embolism (PE), which is a medical emergency and can be fatal. Go to a hospital’s emergency department immediately (do not drive yourself) if you have symptoms of pulmonary embolism such as:

  • Shortness of breath/trouble breathing with no known cause
  • Unexplained cough
  • Coughing up blood
  • Chest pain
  • Increased heart rate
  • Fatigue
  • Passing out (syncope) 

A D-dimer test may also be used to see if treatment for disseminated intravascular coagulation (DIC) is working. 

What Are Normal Results of a D-Dimer Test?

  • A normal D-dimer test result is negative and means problems with blood clotting are unlikely.
  • If the D-dimer test is used to check if treatment is working for disseminated intravascular coagulation (DIC), a normal or decreasing level of D-dimer means the treatment is working.

What Do Abnormal Results of a D-Dimer Test Mean?

An abnormal D-dimer test result would be positive, and it would signify the person may be producing blood clots. A D-dimer test does not tell where the clots are or why they are being produced. 

Other tests are needed to see where clots are located.

D-dimer levels can be positive even when no blood clots are present due to other factors, such as: 

What Causes Blood Clots?

Causes of a blood clot in a vein (venous thrombosis) include:

  • Injury to the leg veins
  • Illness that affects the veins
  • Immobility
  • Broken bone
  • Certain medications
  • Obesity
  • Inherited (genetic) disorders
  • Autoimmune disorders that increase the risk of blood clots
  • Medicines that increase the risk of blood clots (such as certain birth control hormones)

Causes of a blood clot in an artery (arterial thrombosis) include:

Risk factors for both venous and arterial thrombosis include:

Additional risk factors for venous thrombosis include:

  • Use of birth control pills or hormone therapy
  • Pregnancy
  • Injury to a vein, which may occur from surgery, a broken bone, or other trauma
  • Inherited blood clotting disorders
  • A central venous catheter
  • Certain conditions, such as cancer, heart disease, lung disease, or Crohn's disease

Additional risk factors for arterial thrombosis include:


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Reviewed on 9/15/2022

Image source: iStock Images