Test Catalog

Test ID: PTFIB    
PT-Fibrinogen, Plasma

Useful For Suggests clinical disorders or settings where the test may be helpful

Detecting increased or decreased fibrinogen (factor 1) concentration of acquired or congenital origin


Differentiating hypofibrinogenemia from dysfibrinogenemia

Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test

Fibrinogen, also known as factor 1, is a plasma protein that can be transformed by thrombin into a fibrin gel ("the clot"). Fibrinogen is synthesized in the liver and circulates in the plasma as a disulfide-bonded dimer of 3 subunit chains. The biological half-life of plasma fibrinogen is 3 to 5 days.


An isolated deficiency of fibrinogen may be inherited as an autosomal recessive trait (afibrinogenemia or hypofibrinogenemia) and is one of the rarest of the inherited coagulation factor deficiencies.


Acquired causes of decreased fibrinogen levels include acute or decompensated intravascular coagulation and fibrinolysis (disseminated intravascular coagulation), advanced liver disease, L-asparaginase therapy, and therapy with fibrinolytic agents (eg, streptokinase, urokinase, tissue plasminogen activator).


Fibrinogen function abnormalities, dysfibrinogenemias, may be inherited (congenital) or acquired. Patients with dysfibrinogenemia are generally asymptomatic. However, the congenital dysfibrinogenemias are more likely than the acquired to be associated with bleeding or thrombotic disorders. While the dysfibrinogenemias are generally not associated with clinically significant hemostasis problems, they characteristically produce a prolonged thrombin time clotting test. Congenital dysfibrinogenemias usually are inherited as autosomal codominant traits.


Acquired dysfibrinogenemias mainly occur in association with liver disease (eg, chronic hepatitis, hepatoma) or renal diseases associated with elevated fibrinogen levels.


Fibrinogen is an acute-phase reactant, so a number of acquired conditions can result in an increase in its plasma level:

-Acute or chronic inflammatory illnesses

-Nephrotic syndrome

-Liver disease and cirrhosis

-Pregnancy or estrogen therapy

-Compensated intravascular coagulation

The finding of an increased level of fibrinogen in a patient with obscure symptoms suggests an organic rather than a functional condition. Chronically increased fibrinogen has been recognized as a risk factor for development of arterial and venous thromboembolism.

Reference Values Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.

Only orderable as part of a coagulation reflex. For more information see:

ALUPP / Lupus Anticoagulant Profile, Plasma

ALBLD / Bleeding Diathesis Profile, Limited, Plasma

AATHR / Thrombophilia Profile, Plasma

APROL / Prolonged Clot Time Profile, Plasma

ADIC / Disseminated Intravascular Coagulation/Intravascular Coagulation and Fibrinolysis (DIC/ICF) Profile, Plasma


261-595 mg/dL

In normal full-term newborns and in healthy pre-mature infants (30-36 weeks gestation) fibrinogen is near adult levels (>150) and remains at adult levels throughout childhood.

Interpretation Provides information to assist in interpretation of the test results

This test assesses the level of total clottable fibrinogen (see Cautions).

Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances

Fibrinogen assay results may be affected by excess heparin (>1 U/mL), hemoglobin (>100 mg/dL), triglycerides (>700 mg/dL), bilirubin (>15 mg/dL), and by degradation products (fibrin or fibrinogen) in the plasma assayed.

Clinical Reference Recommendations for in-depth reading of a clinical nature

1. Rossi E, Mondonico P, Lombardi A, Preda L: Method for the determination of functional (clottable) fibrinogen by the new family of ACL coagulometers. Thromb Res 1988 Dec;52(5):453-468

2. Palareti G, Maccaferri M, Manotti C, et al: Fibrinogen assays: A collaborative study of six different methods. Clin Chem 1991 May;37(5):714-719