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Thrombin time
Last reviewed: 20.11.2021
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The reference values (norm) of thrombin time are 12-16 seconds.
Thrombin time is the time required to form a fibrin clot in the plasma when thrombin is added to it. It depends only on the concentration of fibrinogen and the activity of thrombin inhibitors (ATIII, heparin, paraproteins) and assesses both the phase of blood coagulation - the formation of fibrin, and the state of natural and pathological anticoagulants.
The definition of thrombin time most often has the following objectives:
- control of heparin therapy, especially when using heparin with a high molecular weight;
- control of fibrinolytic therapy;
- diagnostics of hyperfibrinolytic conditions;
- diagnostics of afibrinogenemia and disfibrinogenemia.
Thrombin time indirectly reflects the concentration of fibrinogen, therefore it lengthens with hereditary and acquired afibrinogenemia and hypofibrinogenemia (with severe liver damage, fibrinolysis, acute DVS-syndrome). Elongated thrombin time and paraproteinaemia.
Determination of thrombin time is one of the most common methods of monitoring the treatment with heparin and fibrinolytics. In these cases, thrombin time should increase by 2-3 times. When performing thrombolytic therapy, it is recommended to determine thrombin time every 4 hours, while remember that if it exceeds the optimal value by more than 2-3 times, the dose of streptokinase should be increased to increase the intake of plasminogen and reduce the formation of plasmin; if the thrombin time decreases below the optimal value, the dose of streptokinase should be reduced so that part of the plasminogen is not blocked in the form of an activator, but completely converted to plasmin.