Quick Facts
- Sample: Blood plasma
- Fasting: Not required
- Turnaround Time: 3-6 business days. May take longer based on weather, holiday, or lab delays.
Benefits
- Diagnose clotting disorders — identify fibrinogen deficiencies causing abnormal bleeding or thrombosis
- Assess cardiovascular risk — elevated fibrinogen links to increased heart disease and stroke risk
- Monitor chronic conditions — track liver disease, inflammation, or disseminated intravascular coagulation (DIC)
- Convenient direct access — order online without physician referral; results delivered quickly and confidentially
- Complement functional tests — distinguish between low fibrinogen quantity versus impaired clotting function
- Pre-surgical screening — evaluate bleeding risk before procedures to ensure safer surgical outcomes
Who Is This Test For?
- Individuals with unexplained bleeding episodes or excessive bruising
- People with abnormal PT or aPTT results requiring further investigation
- Those with family history of clotting or bleeding disorders
- Patients managing liver disease, inflammation, or cancer-related clotting changes
- Smokers and individuals assessing cardiovascular disease risk factors
- Anyone preparing for surgery who needs bleeding risk assessment
How It Works – Just 3 Steps
- Order online — Select your test, pay securely, and schedule your blood draw.
- Visit a lab — Get your blood drawn at any of the 2,000+ convenient lab locations nationwide.
- Receive results — Access results online in your secure account within days.
FAQ
What does this test measure? This test quantifies the amount of fibrinogen protein in your blood plasma, essential for blood clot formation.
How is it different from fibrinogen activity tests? This antigen test measures fibrinogen quantity regardless of function, while activity tests assess how well fibrinogen forms clots.
Do I need to fast before this test? No fasting is required. Consult your provider if you take blood-thinning medications.
What are normal fibrinogen levels? Normal levels range from 200–400 mg/dL; levels below 200 mg/dL increase bleeding risk.
Can this test detect dysfibrinogenemia? Yes, when paired with functional tests, it helps diagnose dysfibrinogenemia—a condition where fibrinogen is present but doesn't function properly.
How soon will I receive my results? Results are typically available within 3–6 business days after sample collection.
More Details
What is the purpose of this test?
The Fibrinogen Antigen Blood Test measures the quantity of fibrinogen—a critical protein produced by your liver that enables blood clot formation to stop bleeding. Unlike functional fibrinogen tests that assess clotting ability, this antigen test specifically quantifies how much fibrinogen protein is present in your plasma. This distinction is crucial for diagnosing conditions like dysfibrinogenemia, where fibrinogen levels appear normal but the protein functions abnormally.
The test helps diagnose bleeding disorders, monitor chronic conditions affecting coagulation, and evaluate inflammation or cardiovascular risk. Fibrinogen acts as an acute-phase reactant, rising during tissue damage, infection, or inflammation, making it a valuable marker for multiple health conditions.
Who would benefit from this test?
This test is particularly valuable for individuals with unexplained bleeding or clotting problems, as fibrinogen deficiency should be considered when PT and aPTT are prolonged. People with liver disease benefit since the liver produces fibrinogen, and advanced liver dysfunction significantly reduces fibrinogen levels. Those with inflammatory conditions, cardiovascular disease risk factors, or family history of clotting disorders can gain insights into their health status.
Individuals undergoing surgery need pre-operative bleeding risk assessment. Pregnant women and those taking oral contraceptives may have elevated levels requiring monitoring. Patients with disseminated intravascular coagulation (DIC) or receiving thrombolytic therapy benefit from regular fibrinogen monitoring to assess treatment effectiveness.
When should I order a Fibrinogen Antigen Blood Test?
Order this test when previous coagulation tests show abnormalities requiring further investigation. If you have unexplained bleeding episodes, easy bruising, or prolonged bleeding after minor injuries, this test helps identify underlying fibrinogen deficiency.
Consider testing if you have liver disease, inflammatory conditions, or cardiovascular risk factors. Before major surgery, this test provides a valuable bleeding risk assessment. If you're monitoring chronic conditions like DIC or tracking effectiveness of thrombolytic therapy, regular fibrinogen testing is essential. When fibrinogen activity tests show low function, this antigen test differentiates between reduced quantity versus impaired function.
How do I interpret the results?
200–400 mg/dL – Normal range
- What it means: Normal levels
- Typical action: No immediate action needed; maintain a healthy lifestyle
<100 mg/dL – Severe deficiency
- What it means: Critically low fibrinogen
- Typical action: Urgent medical evaluation; significant bleeding risk
100–200 mg/dL – Low (mild deficiency)
- What it means: Below normal range
- Typical action: Consult physician; may increase bleeding risk during surgery or trauma
>400 mg/dL – Elevated
- What it means: High fibrinogen levels
- Typical action: Evaluate for inflammation, infection, cardiovascular risk, or tissue damage
Approximately 200 mg/dL is the minimum fibrinogen level required to maintain effective hemostasis.
Disclaimer: Reference ranges may vary by laboratory. Listed ranges are general guidelines and may differ from those used by the performing lab. Always consult your healthcare provider for interpretation.
Pre-test preparation
No fasting is required for this test. Inform your healthcare provider about all medications you're taking, especially blood thinners like heparin, warfarin, or direct thrombin inhibitors, as very high levels may falsely reduce fibrinogen test results by interfering with clot formation. Avoid strenuous exercise immediately before testing, as it may temporarily affect results.
If you're experiencing active bleeding or have recently undergone surgery, inform the lab as these factors may influence interpretation. The test requires a standard blood draw using citrate anticoagulant tubes, processed to platelet-poor plasma for accurate measurement.
How often should I get tested?
- Diagnosed fibrinogen deficiency – Every 3–6 months or as directed by physician
- Monitoring DIC or thrombolytic therapy – Frequently during acute treatment (daily to weekly)
- Chronic liver disease – Every 6–12 months
- Cardiovascular risk assessment – Annually or as part of comprehensive screening
- Pre-surgical screening – Once before major procedures
- General health monitoring (no symptoms) – Not routinely recommended without clinical indication
Testing frequency depends on your specific clinical situation. Individuals with known clotting disorders require more frequent monitoring than those using the test for cardiovascular risk screening. Always follow your healthcare provider's recommendations based on your personal health history and treatment plan.
Why early detection matters
Early detection of fibrinogen abnormalities prevents serious complications. Congenital afibrinogenemia, though rare with only about 150 reported cases, causes infinite PT and aPTT results and severe bleeding starting in infancy—including umbilical cord bleeding and intracerebral hemorrhage. Early diagnosis enables preventive strategies and appropriate management during surgery or trauma.
Identifying dysfibrinogenemia early is crucial since approximately 50% of affected individuals are asymptomatic until discovered through routine testing, yet 25% experience prolonged bleeding after surgery and 20% develop thrombosis. Detecting elevated fibrinogen levels allows early cardiovascular risk intervention through lifestyle modifications and medical management (Mayo Clinic Labs 2023).
For liver disease patients, monitoring fibrinogen helps track disease progression and guide treatment decisions. In DIC cases, prompt detection of declining fibrinogen enables timely intervention, potentially preventing life-threatening bleeding complications.
Related tests you may consider
Prothrombin Time (PT) w/ INR — evaluates the extrinsic clotting pathway and overall clotting function
Partial Thromboplastin Time, Activated (aPTT) — assesses the intrinsic clotting pathway; often prolonged in fibrinogen deficiency
C-Reactive Protein (CRP) — measures inflammation levels that may contribute to elevated fibrinogen and cardiovascular risk
