Thrombin Clotting Time
Haematology marker
TCT
Thrombin Clotting Time
Measures the time for fibrinogen to convert to fibrin after thrombin is added, isolating the final step of clot formation. Sensitive to fibrinogen level and function and to thrombin inhibitors such as heparin and direct thrombin inhibitors.
PED Notes
Thrombin clotting time (also called thrombin time) is a specialised coagulation test, not a routine PED marker. It is prolonged by low or dysfunctional fibrinogen and by anticoagulants that inhibit thrombin (heparin, dabigatran). For enhanced athletes, the more important coagulation issue is androgen-driven erythrocytosis raising haematocrit and clot risk, which the TCT does not measure. No PED shifts the healthy target, so the bodybuilder range equals the standard range.
When high
When prolonged (>21 seconds):
- A prolonged thrombin time points to low fibrinogen (hypofibrinogenaemia), abnormal fibrinogen function (dysfibrinogenaemia), or the presence of a thrombin inhibitor (heparin contamination of the sample, or a direct thrombin inhibitor drug).
- What to do: measure fibrinogen directly and review any heparin or anticoagulant exposure. In severe liver disease fibrinogen synthesis falls, prolonging the TCT.
- This is a specialist result; interpret with a full coagulation panel and clinician input rather than in isolation.
When low
When shortened (<14 seconds):
- A short thrombin time is uncommon and generally not clinically significant. It can occur with very high fibrinogen levels, which rise as an acute-phase reactant with inflammation, infection, or heavy training.
- What to do: no specific action for the TCT itself; if fibrinogen is high, address the underlying inflammatory driver.
History Chart
Reading History
Frequently Asked Questions
Reference Ranges
Standard Range
VitalMetrics Range