Dysfibrinogenemia Workup

Updated: Apr 28, 2022
  • Author: Guy B Faguet, MD; Chief Editor: Perumal Thiagarajan, MD  more...
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Workup

Approach Considerations

The diagnosis is usually based on discrepancies between fibrinogen activity and antigen levels, but could require more specialized techniques for the assessment of fibrinogen function due to some limitations in routine assays. [13] Recommended testing for fibrinogen disorders, and expected results, are as follows:

  • Prothrombin time (PT) – Prolonged

  • Activated partial thromboplastin time (aPTT) – Prolonged

  • Thrombin time (TT) is the most sensitive screening test for dysfibrinogenemias. Expect TT to be prolonged in patients with bleeding tendencies. Shortened TT may occur in patients prone to thrombosis (fibrinogen Oslo I).

  • Reptilase time – Prolonged

Genotype analysis, especially of the FGA gene, should be performed in asymptomatic patients with afibrinogenemia or hypofibrinogenemia [2]

Fibrinogen is measured in plasma using the Clauss method, based on the comparison of thrombin clotting times of dilutions of plasma against a plasma standard. The fibrinogen level may be low, within the reference range, or high. However, a level within the reference range or a high level does not imply that the fibrinogen molecule is fully functioning. For this reason, assess both the clottable (functional) fibrinogen, which should be decreased, and the antigenic fibrinogen (detected by immunoassay), which should be within the reference range. Definitive characterization of the abnormal fibrinogen can be performed in a research laboratory. [14]

Euglobulin clot lysis time may aid in the diagnosis. It is a crude measure of fibrinolytic potential. Elevated values occur when the abnormal fibrinogen results in markedly decreased fibrinolysis.

Although the TT reflects the conversion of fibrinogen to fibrin and is useful for diagnosing coagulation disorders involving abnormal fibrinogen, it does not distinguish between qualitative and quantitative defects. Examination of the amplitude of coagulation curves generated during TT tests may provide additional information to help distinguish between fibrinogen disorders following a low fibrinogen measurement by the Clauss method. [15]

In liver-associated acquired dysfibrinogenemia, fibrinogen levels are usually normal, as opposed to congenital dysfibrinogenemia, in which fibrinogen levels are low normal to deficient. In addition, genetic testing of patients with acquired dysfibrinogenemia will not reveal any mutations associated with the congenital variant.