D Dimer Test

A D-dimer test is usually performed in case of emergencies when there is a sudden onset symptom of chest pain, breathlessness or weakness in arms or legs. This test is also ordered when an individual shows apparent symptoms od DVT, PE or DIC. 

Symptoms of DVT include:

• Leg pain, tenderness in one leg (affected leg)
• Heavy pain in the affected area
• Swelling of the affected leg (oedema)
• Warm skin in the area of the clot
• Discolouration of the affected leg

 Common PE symptoms are:

• Sudden dyspnoea (breathlessness)
• Cough
• Haemoptysis (blood in the sputum)
• Chest pain
• Increased pulse rate (tachycardia)
• Sudden collapse

DIC symptoms include:

• Bleeding gums
• Nausea
• Vomiting
• Seizures 
• Severe muscle pain
• Abdominal pain
• Reduced urine output

More often than not, this test is done in conjunction with prothrombin time (PT), partial thromboplastin time (PTT) and platelet count for diagnosing DIC. A D-dimer test is also performed at regular intervals during DIC therapy to monitor the response to the treatment.

No special preparations are needed for this test.

It is a simple test that takes less than five minutes. An experienced laboratory specialist collects a blood sample from a vein in your arm by inserting a small needle into the vein. A small quantity of blood is withdrawn into a sterile vial or a test tube. A momentary pricking pain is felt when the needle goes in the vein.

There is a minimal risk of pain, light-headedness and bruising at the site of injection with the test. However, at most times, these symptoms disappear quickly. Rarely, an infection may occur at the site of withdrawal of blood.

Normal results: Absence of D-dimer in the blood or negative D-dimer results signify that there are no acute conditions or diseases that have led to the formation and breakdown of a clot and there is a low risk for thrombosis.

Abnormal results: Presence of D-dimer in blood indicate abnormally high fibrin breakdown, which hints towards the presence of a blood clot (thrombus) and its breakdown in the body. However, it cannot help in determining the location or reason for clot formation.

Positive D-dimer results can be seen in the following conditions:

• DIC
• Venous thromboembolism (VTE)
• DVT
• PE
• Stroke
• Heart attack

For confirming the diagnosis as well as the location of DVT, VTE or PE, other diagnostic tests are performed along with the D dimer test. These include ultrasonography, computerised tomography (CT)-angiography, pulmonary angiography and ventilation-perfusion scanning.

A false positivity can be seen in certain normal conditions, such as pregnancy, or in patients aged above 80 years. In addition, D-dimers can show positivity in liver disease, high lipids or triglyceride levels, certain cancers, severe infections (sepsis), chronic heart disease or recent surgery or trauma.

Disclaimer: All results must be clinically correlated with the patient’s complaints to make a complete and accurate diagnosis. The above information is provided from a purely educational point of view and is in no way a substitute for medical advice by a qualified doctor.