Your Clot-Building Protein
Fibrinogen is the raw material for blood clots. When you're injured, thrombin converts fibrinogen into fibrin strands that weave together like a net, trapping platelets and sealing the wound. But fibrinogen is also an acute phase reactant—it rises with inflammation. Chronically elevated fibrinogen increases both clotting risk AND cardiovascular disease.
What is Fibrinogen?
Fibrinogen (Factor I) is a glycoprotein made by the liver. Thrombin converts it to fibrin, the structural scaffold of clots. Also an acute phase reactant (rises with inflammation). Normal: 200-400 mg/dL. Elevated fibrinogen is an independent cardiovascular risk marker.
↑ What High Fibrinogen Means
Two possibilities: acute inflammation (fibrinogen is an acute phase reactant like CRP) or genuine hypercoagulability. Chronically high fibrinogen is an independent cardiovascular risk factor—it makes blood thicker and more prone to clotting.
Common symptoms:
Usually asymptomatic · Increased clot risk (DVT, PE, stroke) · May contribute to cardiovascular events
↓ What Low Fibrinogen Means
Insufficient clot-building material. Bleeding risk. Causes: liver disease (liver makes fibrinogen), DIC (consumed by excessive clotting), or rare inherited afibrinogenemia.
Common symptoms:
Easy bruising · Prolonged bleeding · Poor wound healing
Why It Matters
When normal:
Essential for clot formation and wound healing
Acute phase reactant (helps track inflammation)
Independent cardiovascular risk marker when chronically elevated
Assesses liver synthetic function
Risks if abnormal:
High: increased clot risk, cardiovascular events, stroke
Low: bleeding diathesis, liver failure, DIC
Critical low (<100): significant hemorrhage risk
What Can Cause Abnormal Levels?
Acute Inflammation (high)
55% likelyFibrinogen is an acute phase reactant. Infection, surgery, trauma, autoimmune disease raise it.
Liver Disease (low)
40% likelyLiver produces fibrinogen. Severe liver disease impairs production.
Smoking (high)
Smoking chronically elevates fibrinogen—one mechanism of smoking's cardiovascular risk.
Obesity (high)
Visceral fat promotes chronic inflammation and elevated fibrinogen.
DIC (low)
Consumption: clotting factors including fibrinogen are used up in widespread microvascular thrombosis.
Pregnancy (high)
Fibrinogen increases 50% during pregnancy—physiological preparation for delivery.
What You Can Do
If elevated from inflammation: address underlying cause
Impact: Fibrinogen normalizes when inflammation resolves \u00B7 Timeline: 2-4 weeks
Quit smoking (if applicable)
Impact: Smoking is a major driver of elevated fibrinogen \u00B7 Timeline: 4-8 weeks
Regular exercise
Impact: Moderate exercise lowers fibrinogen \u00B7 Timeline: 4-8 weeks
If lifestyle changes aren't enough:
Omega-3: 2-4g EPA+DHA daily
Impact: Reduces fibrinogen and blood viscosity \u00B7 Timeline: 4-8 weeks
Niacin: 1000-2000mg daily
Impact: Lowers fibrinogen along with other lipid benefits \u00B7 Timeline: 4-8 weeks
Recommended retest: 4-8 weeks; recheck when acute inflammation has resolved for baseline
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