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Introduction ⬇

Fibrinogen is a complex protein (polypeptide) that, with enzyme action, is converted to fibrin. The fibrin, along with platelets, forms the network for the common blood clot. Although it is of primary importance as a coagulation protein, fibrinogen is also an acute-phase protein reactant. It is increased in diseases involving tissue damage or inflammation.

This test is done to investigate abnormal PT, aPTT, and TT and to screen for DIC and fibrin-fibrinogenolysis. It is part of a coagulation panel.

Normal Findings ⬆ ⬇

200–400 mg/dL or 2.0–4.0 g/L

  1. Values of less than 50 mg/dL or less than 0.5 g/L can result in hemorrhage after traumatic surgery.

  2. Values of more than 700 mg/dL or more than 7.0 g/L constitute a significant risk for both coronary artery and cerebrovascular disease.

Clinical Alert

100 mg/dL or 1.0 g/Lpossible critical value, notify the healthcare provide

Procedure ⬆ ⬇

  1. Obtain a 5-mL venous plasma blood sample using the two-tube technique with a collection tube containing sodium citrate (light blue–topped tube). Label the specimen with the patient’s name, date and time of collection, and test(s) ordered.

  2. Place the specimen in a biohazard bag.

Clinical Implications ⬆ ⬇

  1. Increased fibrinogen values occur in:

    1. Inflammation and infections (RA, pneumonia, tuberculosis, streptomycin)

    2. Acute MI

    3. Nephrotic syndrome

    4. Cancer, multiple myeloma, Hodgkin disease

    5. Pregnancy, eclampsia

    6. Various cerebral injuries and diseases

  2. Decreased fibrinogen values occur in:

    1. Liver disease

    2. DIC (secondary fibrinolysis)

    3. Cancer

    4. Primary fibrinolysis

    5. Hereditary and congenital hypofibrinogenemia

    6. Dysfibrinogenemia

Interventions ⬆ ⬇

Pretest Patient Care

  1. Explain test purpose and procedure.

  2. Have the patient avoid aggressive muscular exercise before the test.

  3. Follow guidelines in Chapter 1 for safe, effective, informed pretest care.

Posttest Patient Care

  1. Review test results; report and record findings. Modify the nursing care plan as needed. Counsel the patient regarding abnormal findings; explain the need for possible follow-up testing and treatment. Monitor for DIC and response to treatment. If fibrinogen is low, cryoprecipitate is the preferred product for therapeutic replacement.

  2. Follow guidelines in Chapter 1 for safe, effective, informed posttest care.

Interfering Factors ⬆

  1. High levels of heparin interfere with test results.

  2. High levels of FDPs cause low fibrinogen values.

  3. Oral contraceptives cause high fibrinogen values.

  4. Elevated AT III may cause decreased fibrinogen.

  5. see Appendix E for other drugs that affect test outcomes.