Serum fibrinogen; Plasma fibrinogen; Factor I; Hypofibrinogenemia test
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.
How to Prepare for the Test
No special preparation is needed.
How the Test will Feel
When the needle is inserted to draw blood, some people feel moderate pain. Others feel only a prick or stinging. Afterward, there may be some throbbing or slight bruising. This soon goes away.
Why the Test is Performed
Your doctor may order this test if you have problems with blood clotting, such as excessive bleeding.
The normal range is 200 to 400 mg/dL (2.0 to 4.0 g/L).
Normal value ranges may vary slightly among different laboratories. Some labs use different measurements or may test different specimens. Talk to your doctor about the meaning of your specific test results.
What Abnormal Results Mean
Abnormal results may be due to:
The test may also be performed during pregnancy if the placenta separates from its attachment to the uterus wall (placenta abruption).
There is very little risk involved with having your blood taken. Veins and arteries vary in size, so it may be harder to get a blood sample from one person than another.
Other risks or slight risks from having blood drawn may include:
- Excessive bleeding
- Fainting or feeling lightheaded
- Hematoma (blood accumulating under the skin)
- Infection (a slight risk any time the skin is broken)
This test is most often performed on people who have bleeding disorders. The risk for excessive bleeding is slightly greater in such people than it is for those who do not have bleeding problems.
Chernecky CC, Berger BJ. Fibrinogen (factor I) - plasma. In: Chernecky CC, Berger BJ, eds. Laboratory Tests and Diagnostic Procedures. 6th ed. St Louis, MO: Elsevier Saunders; 2013:525.
Schmaier AH. Laboratory evaluation of hemostatic and thrombotic disorders. In: Hoffman R, Benz EJ Jr, Silberstein LE, Heslop HE, Weitz JI, Anastasi J, eds. Hematology: Basic Principles and Practice. 6th ed. Philadelphia, PA: Elsevier Saunders; 2013:chap 131.