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Fibrinogen test

Also called: Factor I

Fibrinogen is a clotting protein. Low levels raise bleeding risk; it's checked with heavy bleeding and some clotting problems.

SampleA small tube of blood from a vein in your arm
Fasting?Usually not needed
ResultsOften the same day
Good to knowOne result rarely tells the whole story. Your provider looks at your results together with your symptoms, exam, and other tests.

What the test is

It also rises with inflammation and pregnancy.

Why it's done

  • Unexplained bleeding
  • Heavy bleeding after childbirth or injury
  • Possible DIC (a severe clotting disorder)

Getting ready and what happens

  • None.

How the test is done

  • A health worker cleans the skin, puts a band around your arm, and draws blood from a vein with a small needle. It takes a few minutes.

What the results mean

ResultTypical range for adults
FibrinogenAbout 200 to 400 mg/dL

Normal ranges vary from lab to lab and can differ by age, sex, and pregnancy. Your report lists your lab's own range next to each result. A result a little outside the range is often not a problem.

Low

Can mean the body is using up clotting factors or an inherited problem.

Questions to ask your provider

  • What do my results mean for me?
  • Do I need to repeat this test or have other tests?

Risks

A blood draw is very safe. You may have slight pain or a small bruise where the needle went in.

Related conditions

Related tests

Sources

Last updated 2026-11-13.