ThrombinzeitTest

The thrombin time test (TT), sometimes referred to by its direct translation ThrombinzeitTest, is a coagulation assay that measures the conversion of fibrinogen to fibrin after the addition of thrombin to citrated plasma. The result depends on fibrinogen level and function and is highly sensitive to substances that affect thrombin activity, such as inhibitors or contaminants.

Procedure: A standardized amount of thrombin is added to plasma, and the time to clot formation is measured and reported in seconds. Normal ranges vary by method and laboratory, but typical values are in the lower tens of seconds range, around 14 to 18 seconds for many standard reagents.

Clinical uses and interpretation: TT is used to detect abnormalities in fibrinogen, including low fibrinogen levels and dysfibrinogenemia, as well as the presence of inhibitors or anticoagulants that affect thrombin activity. Prolongation of TT suggests hypofibrinogenemia, dysfibrinogenemia, or interference from anticoagulants such as heparin or direct thrombin inhibitors (for example, dabigatran). A normal TT makes severe fibrinogen deficiency unlikely but does not exclude other bleeding disorders.

Limitations and considerations: TT is highly sensitive to heparin contamination in the specimen and to assay conditions, and results can be affected by fibrin degradation products, cryoglobulins, and sample handling. It is not specific for a single disorder and is typically interpreted in conjunction with fibrinogen tests and other coagulation assays rather than as a stand-alone diagnostic test.