Test Talk: fibrinogen

Fibrinogen is a protein that is essential for blood to clot. Since fibrinogen is the precursor to fibrin, no fibrinogen, no fibrin. Without fibrin forming a clot, the patient continues to bleed internally and/or externally. When physicians suspect a clotting disorder in patients who are not receiving anticoagulant therapy, fibrinogen is one of the first tests ordered. It can also be ordered when the patient has an unexplained prolonged protime or aPTT.

Pregnant patients, smokers, post-menopausal women, and patients taking oral contraceptives typically have elevated fibrinogen levels. Patients with inherited or acquired deficiencies have lower fibrinogen levels. Liver disease and consumptive coagulopathies like DIC are acquired deficiencies. Elevated fibrinogen levels can predict an arterial thrombotic event such as a pulmonary embolism or stroke.

Fibrinogen is drawn into citrate (blue stopper) tubes and tested within 4 hours. If not tested immediately, the plasma can be frozen and stored frozen for up to 18 months before testing.

Bibliography

• LabTestsOnline. American Association for Clinical Chemistry. AACC. Accessed 6/26/2020.
• Wu A. Tietz Clinical Guide to Laboratory Tests---Fourth Edition. Elsevier. St. Louis, Missouri. 2006.