What is fibrinogen?
Fibrinogen is a protein that plays an important role in blood clotting and is also known as Factor I. It is the precursor of fibrin. It is the precursor of fibrin, which coats the platelet plug – which forms at the site of a vascular injury – like a net. Fibrinogen is also one of the so-called acute phase proteins. These are various laboratory values that rise in certain diseases.
When is fibrinogen determined?
The physician determines the fibrinogen, for example, if a congenital or acquired fibrinogen deficiency is suspected. The latter can result from liver damage, for example. Other important indications for checking the fibrinogen level are:
- the monitoring of fibrinolytic therapy to dissolve a blood clot (with streptokinase or urokinase)
- the monitoring of a substitution therapy with fibrinogen
- suspicion of pathological excessive activation of blood coagulation (consumption coagulopathy)
Fibrinogen: Normal values
The fibrinogen standard value in the blood is age-dependent. The following normal ranges (reference ranges) apply for children, adolescents and adults:
|
Age |
Fibrinogen normal value |
|
until 4 days |
167 – 399 mg/dl |
|
5 to 30 days |
162 – 462 mg/dl |
|
31 days to 3 months |
162 – 378 mg/dl |
|
4 to 6 months |
150 – 379 mg/dl |
|
7 to 12 months |
150 – 387 mg/dl |
|
13 months to 5 years |
170 – 405 mg/dl |
|
from 6 years |
180 – 350 mg/dl |
Attention: The limit values are method and laboratory dependent. In individual cases, the reference ranges indicated on the laboratory findings apply.
When is fibrinogen decreased?
Some diseases hinder the production of fibrinogen. These include, for example, severe liver diseases such as cirrhosis or acute hepatitis. Other situations that lead to decreased readings are:
- late stage of a consumptive coagulopathy (abnormal activation of blood clotting, also called disseminated intravascular coagulation)
- severe blood loss
- Taking certain medications (for example, asparaginase in the treatment of acute lymphoblastic leukemia).
Newborns also have lower fibrinogen levels than adults. However, this is quite normal at this age and is not an indication of disease.
When is fibrinogen elevated?
Fibrinogen is a so-called acute phase protein. This means it increases when the body has a systemic reaction to certain situations. Other acute-phase proteins include C-reactive protein (CRP) and ferritin. Diseases that lead to an increase in acute phase proteins are:
- Inflammations (e.g. rheumatism, Crohn’s disease)
- Tumors (neoplasms)
- Burns
- Trauma (e.g. surgery)
- Diabetes mellitus and resulting metabolic derailments
- Uremia due to kidney failure (uremia is a poisoning of the blood with substances that should actually be excreted through the urine – in short: urine poisoning)
What to do if fibrinogen is altered?
If fibrinogen is too low, the risk of bleeding is increased. These can be difficult to control. Therefore, if a reduced fibrinogen level is noticed, especially before a planned operation, the physician must determine the cause before the operation and rule out a fibrinogen deficiency disorder.
Chronic diseases with elevated fibrinogen must be optimally controlled. For example, the correct dosage of medication in the case of diabetes or the use of dialysis in the case of kidney failure is of great importance. If fibrinogen is permanently elevated, the risk of cardiovascular disease and stroke increases.
