Fibrinogen blood test
In short
A typical adult fibrinogen result is 200 to 400 mg/dL. A fibrinogen above the range is common, and most often reflects inflammation or a recent illness. It tends to fall again as the cause settles. Always read your result against the range printed on your own report.
A liver-made protein that forms the mesh of a blood clot.
When a blood vessel is injured, fibrinogen is turned into strands that knit together into a clot. Doctors check it to look into bleeding or clotting problems, and during serious illness. It also rises with inflammation anywhere in the body, so a high result does not point to one cause.
Is my Fibrinogen high or low?
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Typical range
| For | Range | Unit |
|---|---|---|
| Adults | 200–400 | mg/dL |
| Adults | 2–4 | g/L |
Typical ranges for adults. Labs differ a little, so the range printed next to your result is the one to go by.
If your Fibrinogen is high
A fibrinogen above the range is common, and most often reflects inflammation or a recent illness. It tends to fall again as the cause settles.
Common reasons
- A recent infection, injury or surgery
- Inflammation anywhere in the body, including long-term conditions such as arthritis
- Pregnancy, birth control pills or hormone therapy
- Smoking
- Carrying extra weight, and getting older
- Less often: kidney disease, or a long-lasting illness such as cancer
If your Fibrinogen is low
A fibrinogen below the range is less common than a high one. A very low level matters more, because clots may not form well.
Common reasons
- Natural variation: some labs' ranges start lower, near 150 mg/dL
- Heavy bleeding or large transfusions, which use up or dilute fibrinogen
- Some clot-dissolving medicines given in hospital
- Less often: advanced liver disease, since the liver makes fibrinogen
- Less often: DIC, a serious illness in which clotting proteins get used up
- Less often: an inherited low fibrinogen, present from birth
What can throw it off
A recent infection, injury or surgery can keep fibrinogen raised for a few weeks.
Questions to take to your appointment
- 1Could a recent illness or inflammation explain this?
- 2Do my other clotting tests point the same way?
- 3Should it be rechecked once I'm well?
Read together with
Doctors rarely read Fibrinogen alone. These usually sit next to it.
- PTHow many seconds a blood sample takes to form a clot.
- aPTTA clotting time, in seconds, that checks another group of clotting proteins.
- D-dimerA fragment released when the body breaks down a blood clot.
- PlateletsTiny cell pieces that help the blood clot.
- CRPA protein the liver makes when there is inflammation.
Quick answers
What is the fibrinogen blood test?
Fibrinogen: A liver-made protein that forms the mesh of a blood clot. When a blood vessel is injured, fibrinogen is turned into strands that knit together into a clot. Doctors check it to look into bleeding or clotting problems, and during serious illness. It also rises with inflammation anywhere in the body, so a high result does not point to one cause.
What is a normal fibrinogen level?
For most adults, fibrinogen is typically 200 to 400 mg/dL. Some countries print it in g/L, so check the unit first. Labs differ a little, so the range printed next to your result is the one to go by.
What does a high fibrinogen mean?
A fibrinogen above the range is common, and most often reflects inflammation or a recent illness. It tends to fall again as the cause settles. Common reasons include a recent infection, injury or surgery; inflammation anywhere in the body, including long-term conditions such as arthritis; pregnancy, birth control pills or hormone therapy; and smoking. A doctor reads it together with your other results and how you feel.
What does a low fibrinogen mean?
A fibrinogen below the range is less common than a high one. A very low level matters more, because clots may not form well. Common reasons include natural variation: some labs' ranges start lower, near 150 mg/dL; heavy bleeding or large transfusions, which use up or dilute fibrinogen; some clot-dissolving medicines given in hospital; and less often: advanced liver disease, since the liver makes fibrinogen.
What can affect my fibrinogen result?
A recent infection, injury or surgery can keep fibrinogen raised for a few weeks.
What should I ask my doctor about my fibrinogen?
Questions worth taking to the appointment: Could a recent illness or inflammation explain this? Do my other clotting tests point the same way? Should it be rechecked once I'm well?
What this page can’t do
It reads each number on its own.
Doctors read results together — ALT with AST, ferritin with hemoglobin, TSH with free T4. A pattern says more than any single flag.
It doesn't know you.
Your age, your medicines, how you feel and your last result all change what a number means.
It doesn't remember.
Close this page and your results are gone. That's on purpose: nothing was ever sent to us.
We also make Vita: Health Coach, an app for those parts. It reads your whole report with your medicines and history in mind, answers follow-up questions in plain words, and keeps your reports in one place — for you and for the people you look after.
Vita: Health Coach on the App StoreSources
- MedlinePlus — Fibrinogen blood test
- ABIM — Laboratory test reference ranges (January 2026)
- UW Medicine Laboratory Test Guide — Fibrinogen
Stuck on a word? See the medical words. How we choose our sources. More about Vita Health Coach.