Lexicon
Fibrinogen
Definition
Fibrinogen is a large glycoprotein, synthesized primarily in the liver, and is the most abundant blood coagulation factor. [1] Fibrinogen is a classical positive acute-phase reactant protein and is an independent predictor of coronary heart disease events. [2] In prospective studies fibrinogen was found to be an independent predictor of myocardial infarction in both sexes and of stroke in men, providing information on risk over and above that from established risk factors. [3]
How it works
The final stage of blood clot formation is the conversion of soluble fibrinogen to insoluble fibrin, the polymeric scaffold for blood clots that stop bleeding or obstruct blood vessels. [1] Fibrinogen may contribute to atherothrombosis by promoting atherosclerosis, acting as an essential component of platelet aggregation, and increasing plasma viscosity. [3] Plasma fibrinogen concentrations vary widely among populations and increase with age, are consistently higher in women than in men and rise after menopause, with smoking the most important lifestyle correlate. [4] Fibrinogen and its end product fibrin interact with numerous plasma proteins and cells, and quantitative or qualitative fibrinogen defects are associated with bleeding, thrombosis, and inflammation, as well as diseases affected by these processes [5]
Connected concepts
How it's measured
The Clauss assay is the most commonly performed fibrinogen assay and uses diluted plasma in which clotting is initiated with a high concentration of reagent thrombin. [6] Clotting rate assays remain the routine method of choice for investigating, monitoring and treating bleeding disorders associated with low fibrinogen, while immunoassays are useful for differentiating hypofibrinogenaemia from dysfibrinogenaemia and for assessing cardiovascular risk. [2] Four main types of assay are used to determine fibrinogen, namely clotting rate (Clauss), clottable protein, precipitation and immunological assays, and results can differ between methods. [7]
What levels mean
The normal plasma concentration of fibrinogen is 1.5 to 3.5 g/L. [1] Severe hypofibrinogenaemia below 1 g/L that persists despite fresh frozen plasma replacement may be treated with fibrinogen concentrate or cryoprecipitate. [8] In advanced liver disease a fibrinogen above 120 mg/dL is among the transfusion thresholds that may optimize clot formation for active bleeding or high-risk procedures.
Community knowledge
## Vascular Inflammation Marker
The longevitydocs community's collective insight and shared knowledge on this concept — across text, video, audio and images from members and faculty, reserved for members.
Learn about our Membership planReferences
- 1.Litvinov RI, Pieters M, de Lange-Loots Z, Weisel JW. Fibrinogen and Fibrin. Subcell Biochem · 2021
- 2.Lowe GD, Rumley A, Mackie IJ. Plasma fibrinogen. Ann Clin Biochem · 2004
- 3.Heinrich J, Assmann G. Fibrinogen and cardiovascular risk. J Cardiovasc Risk · 1995
- 4.Folsom AR. Epidemiology of fibrinogen. Eur Heart J · 1995
- 5.Wolberg AS. Fibrinogen and fibrin: synthesis, structure, and function in health and disease. J Thromb Haemost · 2023
- 6.Winter WE, Flax SD, Harris NS. Coagulation Testing in the Core Laboratory. Lab Med · 2017
Community discussion
Clinical pearls and discussion posted by community members on this concept — signed contributions, reserved for members.
Learn about our Membership plan