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D-Dimer

Blood clotting Biomarker

Sample Needed

Collection Type: Blood

Body System

Related System: Blood clotting

Overview

D‑dimer is a small protein fragment produced when a blood clot is broken down by the body’s fibrinolytic system. The D‑dimer test measures the amount of this fragment in blood and indicates recent or ongoing clot formation and degradation. It is commonly used when venous thromboembolism (deep vein thrombosis or pulmonary embolism) or disseminated intravascular coagulation (DIC) are suspected. Symptoms that warrant testing include sudden shortness of breath, chest pain, unexplained leg swelling or pain, and signs of bleeding with shock. Results can vary with age (higher with increasing age), pregnancy, recent surgery/trauma, active infection, cancer, and inflammatory conditions; some assays also report results in different units (ng/mL FEU or μg/mL FEU).

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Test Preparation

A duly filled coagulation requisition form (Annexure - CR/05) is mandatory for sample collection
Kindly provide complete clinical details and medication history or doctor's prescription
this information is important for correlation of your test results

Why Do I Need This Test

Profile: Blood clotting - Symptoms: Sudden shortness of breath, pleuritic chest pain, unilateral leg swelling/pain, unexplained bleeding or shock - Conditions diagnosed/monitored: Suspected DVT, pulmonary embolism, DIC, monitoring anticoagulation complications - Reasons for abnormal levels: Active thrombosis, recent surgery/trauma, infection, inflammation, cancer, pregnancy, liver disease - Biological meaning: Elevated D‑dimer indicates increased clot formation and breakdown; low D‑dimer makes recent significant thrombosis unlikely - Lifestyle/family history: Recent immobility, smoking, cancer history, personal/family history of thrombosis increase the need for testing

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Understanding Test Results

A D‑dimer below the cutoff (typically <500 ng/mL FEU) in a patient with low-to-moderate clinical probability effectively rules out acute venous thromboembolism (high negative predictive value).
Values just above the cutoff (≈500–2,000 ng/mL FEU) are nonspecific and may reflect recent surgery/trauma, infection, inflammation, cancer, or early/mild thrombosis.
Moderately high values (≈2,000–5,000 ng/mL FEU) raise concern for active, more extensive thrombosis or evolving DIC.
Very high values (>5,000 ng/mL FEU) are commonly seen with major clot burden, severe DIC, or sepsis and warrant urgent evaluation.
Age-adjusted cutoffs (age 10 ng/mL FEU for patients >50 years) are often used to reduce false positives in older adults.
Low values are rarely diagnostic of an alternate problem but are clinically useful to exclude significant acute clot when pretest probability is low.

Normal Range

0-500 ng/mL FEU OR 0-0.5 μg/mL FEU

FAQs

Q: What does D-dimer high mean?

A: A high D‑dimer means increased fibrin breakdown in the blood, suggesting recent or ongoing clot formation and degradation. It’s sensitive but non‑specific: elevated levels can reflect deep vein thrombosis, pulmonary embolism, disseminated intravascular coagulation, surgery, trauma, infection, inflammation, pregnancy, or cancer. A raised result usually prompts further evaluation (imaging or specialist review) rather than confirming a diagnosis alone.

Q: What infections can cause high D-dimer?

A: Various infections can raise D-dimer by activating coagulation and fibrinolysis. Common causes include severe bacterial infections and sepsis, pneumonia, infective endocarditis, urinary tract infections with systemic involvement, and viral infections such as COVID-19 and influenza. Fungal and severe parasitic infections may also elevate levels. Elevated D-dimer in infection often reflects inflammation-associated clot formation rather than specific thromboembolism.

Q: Why is my D-dimer positive but no clot?

A: A positive D‑dimer means there’s increased fibrin breakdown but isn’t specific for a new clot. Levels rise after surgery or trauma, with infection or inflammation, in pregnancy, cancer, liver disease, and with aging, or after a recent treated clot. False positives and assay variability occur. Clinical assessment and imaging (e.g., ultrasound or CT pulmonary angiography) are needed to confirm or exclude thrombosis.

Q: What is the role of the D-dimer?

A: D-dimer is a fibrin degradation product released when blood clots are broken down. Measuring D-dimer helps detect active clot formation and fibrinolysis; it’s used to rule out venous thromboembolism (deep vein thrombosis, pulmonary embolism) and to support diagnosis of disseminated intravascular coagulation. Results are non-specific—levels rise with age, inflammation, infection, surgery, or pregnancy—so clinical assessment and imaging guide management.

Q: What cancers cause high D-dimer?

A: Many cancers raise D-dimer, especially those with high thrombotic risk or advanced disease: pancreatic, lung, gastrointestinal (colorectal, stomach), ovarian, and metastatic cancers. Hematologic malignancies (leukemia, lymphoma, multiple myeloma) can also elevate D-dimer. Elevations reflect tumor-related coagulation activation; D-dimer is nonspecific and may rise with thrombosis, inflammation, surgery, or infection, so results need clinical correlation.

Q: What are the five warning signs of a blood clot?

A: Five warning signs of a blood clot: sudden swelling in one leg or arm, localized pain or tenderness (often in the calf), redness and warmth over the area, unexplained shortness of breath or rapid breathing, and chest pain or a fast/irregular heartbeat (which may indicate a pulmonary embolism). Seek urgent medical attention if any occur.