Is my Fibrinogen normal?
Free blood test checker · Standard + longevity-optimal ranges
What is a normal Fibrinogen level?
Fibrinogen is a liver-produced glycoprotein that serves dual roles: it is essential for blood clot formation (converted to fibrin by thrombin) and it is a major acute-phase reactant that rises with inflammation. Normal is 200-400 mg/dL. Above 500 mg/dL is critically elevated. Elevated fibrinogen independently predicts cardiovascular events, stroke, and venous thromboembolism. It increases blood viscosity, promotes platelet aggregation, and enhances fibrin deposition in atherosclerotic plaques — making it a direct link between inflammation and thrombosis.
| Range | Values |
|---|---|
| Standard Reference | 200–400 mg/dL |
| High Risk | > 500 mg/dL |
What causes abnormal Fibrinogen levels?
Elevated fibrinogen is caused by acute and chronic inflammation (infection, autoimmune disease), smoking (one of the strongest modifiable elevators), obesity, diabetes, metabolic syndrome, pregnancy, oral contraceptive use, cancer, and post-surgical states. Low fibrinogen can indicate severe liver disease (reduced synthesis), disseminated intravascular coagulation (DIC), or inherited fibrinogen disorders.
When should you see a doctor?
See your doctor if fibrinogen is above 400 mg/dL persistently, especially with other cardiovascular risk factors. Above 500 mg/dL requires evaluation for underlying inflammatory conditions. If fibrinogen is below 150 mg/dL, investigate for liver disease or clotting disorders. Seek urgent care if you have signs of abnormal clotting (unexplained DVT, PE, or excessive bleeding).
Fibrinogen and longevity
Fibrinogen occupies a unique position as both an inflammatory biomarker and a direct mediator of cardiovascular disease. The Framingham Heart Study and European MONICA project demonstrated that fibrinogen independently predicts myocardial infarction and stroke with predictive power comparable to LDL cholesterol. Mechanistically, fibrinogen increases blood viscosity, which impairs microcirculation and oxygen delivery to tissues. It promotes platelet aggregation and forms the structural scaffold of blood clots within atherosclerotic plaques. Elevated fibrinogen also reflects the hepatic acute-phase response — the liver upregulates fibrinogen production in response to IL-6, the same inflammatory cytokine that drives CRP elevation. Regular aerobic exercise is the most evidence-based intervention for lowering fibrinogen, reducing levels by 10-15% through improved endothelial function and anti-inflammatory effects.
Where to get a Fibrinogen test
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Related biomarkers
These biomarkers are often tested alongside Fibrinogen for a more complete picture.
Frequently asked questions
What is a normal fibrinogen level?
Why is fibrinogen a cardiovascular risk factor?
How can I lower fibrinogen?
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Sources: Reference ranges based on AHA/ACC, ADA, and AACE clinical guidelines. Biological variation data from Ricos/Westgard database. Longevity-optimal ranges reflect targets used by preventive and functional medicine practitioners.
Last reviewed: April 2026. This tool provides general health information and is not a substitute for professional medical advice, diagnosis, or treatment. Always consult your healthcare provider about your specific results.