Clotting
Fibrinogeen
A clotting protein from the liver that also rises with inflammation; mainly used when investigating a bleeding tendency.
Everything about this testWhat it measures
Fibrinogen is a protein that the liver makes and that is needed for blood clotting. When there is a wound, the body converts fibrinogen into fibrin: threads that, together with platelets, form a clot and stop the bleeding. Fibrinogen is also an acute-phase protein: with inflammation, infection, surgery or injury, the liver temporarily makes more of it. The value therefore says something about clotting and something about inflammation.
- A shortage of fibrinogen with a bleeding tendency, severe liver disease or severe consumption of clotting factors
- Inflammation or tissue damage, as an acute-phase protein
- Rarely: a hereditary disorder in the production or function of fibrinogen
High
According to the Dutch Society for Clinical Chemistry (NVKC), a raised fibrinogen usually fits an inflammation, infection, injury or surgery in the preceding weeks; the value returns to normal once that has passed. Smoking, overweight, pregnancy, the contraceptive pill and older age also go with a higher value. In research, a higher fibrinogen is linked to a slightly higher risk of cardiovascular disease, but that does not mean that a high value will lead to a heart attack or thrombosis in you. A raised value does not cause symptoms by itself.
Low
According to the Dutch Society for Clinical Chemistry (NVKC), a low fibrinogen means there is less of this clotting factor, so blood cannot clot as well. Causes are severe liver disease, major blood loss, clot-dissolving medicines and a severe derailment of clotting in very ill people. Rarely, there is a hereditary deficiency. Symptoms that may go with it are bruising easily, prolonged bleeding after a small wound or dental treatment and heavy blood loss during periods. A slightly low value without symptoms usually has no consequences.
If your result is abnormal
With a raised fibrinogen without symptoms, usually no separate testing follows; the GP can repeat the measurement once a recent infection or inflammation has passed, possibly together with CRP. With a low fibrinogen or a bleeding tendency, additional clotting tests follow and, if needed, a referral to the internist-hematologist.
Reliability
As a measure of the risk of cardiovascular disease, fibrinogen adds little to age, sex, smoking, blood pressure and cholesterol; the Dutch medical specialists' guideline (FMS) on cardiovascular risk management names fibrinogen as an inflammation marker with little added value for the risk estimate. Because fibrinogen rises with any inflammation, a single raised value says little about the cause. When investigating a bleeding tendency, fibrinogen is assessed together with other clotting tests.
Limitations
- An infection, inflammation, surgery or injury in the weeks before the blood draw temporarily raises the value.
- Smoking, pregnancy, the contraceptive pill and hormone treatment raise fibrinogen.
- A difficult blood draw or a tube that is not properly filled can disturb the result; clotting tests are sensitive to how the sample is collected.
- Clot-dissolving medicines lower the value.
How common is this
There are no Dutch figures on how often an abnormal fibrinogen occurs. A temporarily raised value due to inflammation or infection is common. A hereditary shortage of fibrinogen is very rare.
Who is this useful for
Useful with a bleeding tendency, such as bruising easily or prolonged bleeding, usually together with other clotting tests, and with severe liver disease. In healthy adults a single value says little, and for estimating the risk of cardiovascular disease, blood pressure, cholesterol, smoking and glucose are more important. As a measure of inflammation, CRP is more common.
Downsides and risks
- A raised fibrinogen can cause needless worry about cardiovascular disease or thrombosis, while the value says little about that question.
- A temporarily raised value due to a recent infection can lead to unnecessary follow-up testing.
Sources
Always discuss an abnormal result with your GP. If a result is strongly abnormal, we try to reach you as soon as possible. Read your result yourself as well and contact your GP if in doubt. A test does not make a diagnosis. Read more about risks and results