Finding the right tests…
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Finding the right tests…
Serology
Fibrinogen is a protein your liver makes and releases into your blood, where it is the final building block converted into fibrin - the mesh that holds a blood clot together. This test measures how much fibrinogen is in your plasma, collected in a citrate tube that stops the sample from clotting before it reaches the lab. Doctors order it when investigating unexplained bleeding, before some surgeries, and as part of the workup for disseminated intravascular coagulation, where fibrinogen gets used up faster than the liver can replace it. Your result is compared against the lab's own reference range to see whether your level sits low, normal, or high.
The result is reported in milligrams per decilitre, checked against the lab's own reference range. A low level means either your body is not making enough fibrinogen, or something is consuming it faster than it can be replaced - severe bleeding, disseminated intravascular coagulation, and liver disease can all do this. The test is drawn into a citrate tube specifically because fibrinogen testing needs plasma that has not started clotting on its own, which would use up the very protein being measured.
Fibrinogen is the last step before a clot actually forms - it gets converted into fibrin strands that trap platelets and red cells into a stable clot. Without enough of it, even a normal platelet count and normal PT/PTT cannot produce a clot that holds.
- Disseminated intravascular coagulation, where clotting factors are consumed throughout the body - A rare inherited fibrinogen deficiency, present from birth - Severe bleeding, since fibrinogen is lost along with the blood - Advanced liver disease, since the liver is where fibrinogen is made - Placental separation during pregnancy
This sample has to be drawn into a tube containing citrate, an additive that binds calcium and stops the clotting cascade inside the tube, because testing plasma that has already started clotting would give a falsely low reading. Getting the sample handling right is as much a part of an accurate result as the lab analysis itself.
A single low fibrinogen result usually gets repeated and read alongside platelet count, PT, and PTT, since these tests move together in most of the conditions that lower fibrinogen.
A typical adult range runs from about 200 to 400 mg/dL (2.0 to 4.0 g/L), though the exact cutoff can vary slightly by lab. Ranges vary by lab, so check the reference interval printed on your own report.
Citrate binds the calcium your blood needs to clot, keeping the sample liquid until it reaches the lab. Without it, the fibrinogen being measured would already be partly used up before testing, giving a falsely low result.
It can mean your body isn't making enough fibrinogen, or that something - severe bleeding, DIC, or liver disease - is consuming it faster than it's replaced. Your doctor reads the result alongside your platelet count and other clotting tests to narrow down the cause.
This page is general information about the test, not medical advice. Your own report's reference ranges apply — please discuss your results with your doctor.
Yes, since the liver is where fibrinogen is produced, advanced liver disease can reduce how much is made. This is one reason fibrinogen is sometimes tracked as part of monitoring chronic liver conditions.
There is no fixed fasting rule for this test on its own. Ask your doctor or the centre when you book, since instructions can change if other tests are being drawn at the same time.
It's usually ordered together with platelet count, PT, and PTT, since these move together in the conditions that most often affect fibrinogen, such as DIC and severe bleeding.