Type of test: Blood

Normal findings

 Adult: 200-400 mg/dL or 2-4 g/L (SI units)

Newborn: 125-300 mg/Dl

 Possible critical values: < 100 mg/dL

Test explanation and related physiology

 Fibrinogen is essential to the blood-clotting mechanism. It is part of the common pathway in the coagulation system. (See discussion of coagulating factors, p. 250). Fibrinogen, which is produced by the liver, is also an acute-phase protein reactant. It rises sharply during instances of tissue inflammation or necrosis. High levels of fibrinogen have been associated with an increased risk of coronary heart disease, stroke, myocardial infarction, and peripheral arterial disease. This makes fibrinogen an important risk factor for cardiovascular disease.

Fibrinogen is used primarily to aid in the diagnosis of suspected bleeding disorders. This testing is used to detect increased or decreased fibrinogen concentration of acquired or congenital origin. It is also used for monitoring the severity and treatment of disseminated intravascular coagulation and fibrinolysis.

Reduced levels of fibrinogen can be seen in patients with liver disease, malnourished states, and consumptive coagulopathies (e.g., disseminated intravascular coagulation). Large-volume blood transfusions are also associated with low levels of fibrinogen because banked blood does not contain fibrinogen. Reduced levels of fibrinogen will cause a prolonged prothrombin time and partial thromboplastin time.

Interfering factors

 • Blood transfusions within the past month may affect test results.

• Diets rich in omega-3 and omega-6 fatty acids reduce fibrinogen levels.

* Drugs that may cause increased levels include estrogens and oral contraceptives.

* Drugs that may cause decreased levels include anabolic steroids, androgens, l-asparaginase, phenobarbital, streptokinase , tissue plasminogen activators (e.g., urokinase), and valproic acid.

Procedure and patient care

• See inside front cover for Routine Blood Testing.

 • Fasting: no

• Blood tube commonly used: blue

Abnormal findings

- Increased levels

- Acute inflammatory reactions (e.g., rheumatoid arthritis, glomerulonephritis)

- Trauma

- Acute infection (e.g., pneumonia)

- Coronary heart disease

- Cigarette smoking

- Pregnancy

- Cerebrovascular accident

- Myocardial infarction

- Peripheral arterial disease

Decreased levels

- Liver disease (e.g., hepatitis, cirrhosis)

-Consumptive coagulopathy

-Fibrinolysins

-Congenital afibrinogenemia

- Advanced carcinoma

- Malnutrition

-Large-volume blood transfusion

- Hemophagocytic lymphohistiocytosis