The fibrinogen assay performed in the clinical laboratory is a quantitative measure of factor I. This assay is used to determine whether there is enough fibrinogen present to allow for normal clotting. It is performed in cases of an unexpected, prolonged bleeding event, or an unexpected abnormal PT and/or aPTT. Additionally, it is also used to aid in the diagnosis of disseminated intravascular coagulation (DIC).
The fibrinogen reference range is typically around 200-400 mg/dL. Fibrinogen levels <100 mg/dL are often associated with free bleeding, or impaired hemostatic function.