Definition
Fibrinogen is a protein produced by the liver. This protein helps stop bleeding by helping blood clots to form. A blood test can be done to tell how much fibrinogen you have in the blood.
Alternative Names
Serum fibrinogen; Plasma fibrinogen;
Factor I; Hypofibrinogenemia test
Why the Factor I is Performed
Your doctor may order this test if you have problems with blood clotting, particularly if you have excessive bleeding.
How the Factor I is Performed
Blood is drawn from a vein, usually on the inside of the elbow or the back of the hand. The puncture site is cleaned with antiseptic, and an elastic band is placed around the upper arm to apply pressure and restrict blood flow through the vein. This causes veins below the band to fill with blood.
A needle is inserted into the vein, and the blood is collected in an air-tight vial or a syringe. During the procedure, the band is removed to restore blood flow. Once the blood has been collected, the needle is removed, and the puncture site is covered to stop any bleeding.
For an infant or young child, the area is cleansed with antiseptic and punctured with a sharp needle or a lancet. The blood may be collected in a pipette (small glass tube), on a slide, onto a test strip, or into a small container. Cotton or a bandage may be applied to the puncture site if there is any continued bleeding.
How to Prepare for the Factor I
There is no special preparation needed.
How the Factor I Will Feel
When the needle is inserted to draw blood, some people feel moderate pain, while others feel only a prick or stinging sensation. Afterward, there may be some throbbing.
Risks
- Excessive bleeding
- Fainting or feeling light-headed
- Hematoma (blood accumulating under the skin)
- Infection (a slight risk any time the skin is broken)
- Multiple punctures to locate veins
Considerations
Veins and arteries vary in size from one patient to another and from one side of the body to the other. Obtaining a blood sample from some people may be more difficult than from others.
Normal Results
The normal range is 200-400 milligrams per deciliter (mg/dL).
What Abnormal Results Mean
Abnormal results may be due to:
- Excessive fibrinogen use (as in disseminated intravascular coagulation)
- Fibrinolysis
- Hemorrhage
- Lack of fibrinogen production (acquired or from birth)
Additional conditions under which the test may be performed:
- Hemophilia A
- Hemophilia B
- Placenta abruptio
