Fibrinogen
A protein essential for blood clotting that also rises with inflammation.
Typical reference range
| Range | Unit |
|---|---|
| 2–4 | g/l |
What Fibrinogen measures
Fibrinogen is a protein made by the liver that is essential for blood clotting. When you are injured, fibrinogen is converted into fibrin, the threadlike protein that forms the mesh holding a clot together. Without enough of it, the body struggles to seal off bleeding effectively.
Fibrinogen is also an acute-phase reactant, meaning its level rises in response to inflammation anywhere in the body. Because of this dual nature, it is used in two ways: as part of assessing how well the blood clots, and sometimes as a general marker of inflammation. A clinician reads it alongside other clotting tests, inflammatory markers, and your overall clinical picture rather than on its own.
What a high Fibrinogen can mean
A high fibrinogen most commonly reflects the body's acute-phase response, in which levels rise during inflammation, infection, or tissue injury. Because it climbs in so many settings, a raised value points to activity somewhere in the body rather than to any single cause.
Fibrinogen can also be higher for reasons unrelated to acute illness, including:
- Pregnancy, during which levels naturally increase
- Smoking and certain other conditions
Persistently high fibrinogen has been associated with greater cardiovascular risk, though it is one contributor among many rather than a diagnosis on its own. A clinician interprets a raised value in context, weighing it against your symptoms, other inflammatory markers, and your broader health before deciding whether any follow-up is warranted.
What a low Fibrinogen can mean
A low fibrinogen can arise from two broad mechanisms. The first is reduced production, since the protein is made by the liver, significant liver disease can lower how much is available. The second is increased consumption, where fibrinogen is used up faster than it can be replaced.
Increased consumption may occur with large clots or with a serious, potentially life-threatening condition called disseminated intravascular coagulation (DIC), in which clotting is activated throughout the body. Rarely, low fibrinogen is inherited.
Because fibrinogen matters so directly for the ability to form clots, a genuinely low value is taken seriously and followed up promptly to find and address the underlying reason. A clinician interprets the result together with your other clotting tests, symptoms, and overall situation rather than treating the number alone.
Track your Fibrinogen over time in Quanome — it reads your lab reports (PDF or photo) on your device, charts each marker against its range, and an AI coach explains what your trends mean alongside your Apple Health and DNA.