Fibrinogen

Overview

Fibrinogen measures a soluble plasma glycoprotein synthesized by the liver that serves as the precursor to fibrin during blood clotting. As an acute phase reactant, it rises rapidly in response to inflammation, tissue injury, or infection. Elevated levels indicate inflammation, pregnancy, or thrombotic risk, while low levels suggest bleeding disorders, liver disease, or consumptive coagulopathy. Fibrinogen testing is clinically useful for assessing coagulation status, monitoring disseminated intravascular coagulation (DIC), and evaluating inflammatory conditions.

Clinical Use Cases

  • Diagnosing afibrinogenemia or dysfibrinogenemia.
  • Monitoring disseminated intravascular coagulation (DIC).
  • Evaluating liver synthetic function.
  • Assessing thrombotic risk in cardiovascular disease.

Specimen Types

  • Plasma (sodium citrate).
  • Serum (less common).

Measurement Methods

  • Clauss method (functional clot-based assay).
  • PT-derived fibrinogen (calculated from prothrombin time).
  • Immunological assays (nephelometric, turbidimetric).

Test Preparation and Influencing Factors

  • Avoid heparin contamination; use proper citrate tubes.
  • Acute phase reactant: elevated by inflammation, pregnancy, estrogen therapy.
  • Decreased by liver disease, DIC, massive transfusion.
  • Sample hemolysis or lipemia interferes with assays.

Synonyms

  • Coagulation Factor I.
  • Functional fibrinogen.

Further Reading

  • Fibrinogen Test; MedlinePlus