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D-dimer (Fibrin Degradation Products) by Immunoassay

Published: August 9, 2026Updated: August 16, 2026

This test measures the presence of D-dimer, a breakdown product of blood clots. It helps assess whether you may have a condition involving abnormal clot formation.

Quick summary

["D-dimer helps diagnose or rule out blood clots in your veins or arteries."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 16, 2026Editorial policy

Key facts at a glance

LOINC
63520-1
Short code
DXA proto
Synonyms
DXA proto
Category
coagulation
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
phenx
Specimen volume
5 mL
Stability
Room temperature: 4h, Refrigerated: 24h, Frozen: 7d
Hemolysis max
500
Lipemia max
1000
Icterus max
500
TAT
4–24 hours
Order
routine

What Is D-Dimer?

D-dimer is a protein fragment that forms when blood clots dissolve naturally in your body. High levels may suggest recent clot activity, such as deep vein thrombosis (blood clots in veins) or pulmonary embolism (clots in the lungs). This test is often used alongside other tests to help diagnose these conditions.

Why Might You Need This Test?

Your healthcare provider may order a D-dimer test if you have symptoms like swelling, pain, or shortness of breath that could indicate a blood clot. It may also be used in people with a higher risk of clots, such as those who have recently had surgery or are taking blood thinners.

How Is the Test Done?

A blood sample is taken from a vein in your arm. The blood is then processed to detect D-dimer levels using an immunoassay method, which identifies the protein fragment in your blood.

What Do Results Mean?

Results are not given in absolute numbers but are interpreted in the context of your symptoms, medical history, and other tests. Very low levels are usually normal, while very high levels may raise concern for clotting issues.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

D-dimer

Frequently asked questions

What causes elevated D-dimer levels?
Elevated D-dimer levels can occur due to conditions like deep vein thrombosis, pulmonary embolism, pregnancy, severe infections, or certain cancers. It can also be affected by medications, pregnancy, or other medical conditions that increase clot breakdown.
Can D-dimer levels be affected by medications?
Yes, certain medications like blood thinners (anticoagulants) can affect D-dimer levels. If you are taking these medications, your results may be interpreted differently by your healthcare provider.
How soon after a blood clot do D-dimer levels rise?
D-dimer levels typically rise shortly after a clot forms, often within hours to a few days. However, the exact timing can vary depending on the individual and the severity of the clot.
  1. 1
    MedlinePlus — Laboratory TestsSource
  2. 2
    Lab Tests OnlineSource
  3. 3
    Mayo Clinic — Tests & ProceduresSource

Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.

This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.

Medical Disclaimer

This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.

If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.

Medically reviewed by WellAlly Editorial Team Last reviewed August 16, 2026. · Read our editorial policy