Thrombin Time Test
Thrombin Time (TT) measures how long it takes fibrinogen to convert to fibrin — the final step of the clotting cascade. It specifically evaluates fibrinogen function and detects the presence of thrombin inhibitors such as heparin.
Turnaround 36 hours, estimate Turnaround: up to 36 hours after your blood draw (estimate).
Reference Ranges
No established reference range
There is no generally applicable reference interval for thrombin time. The result depends on the reagent the laboratory uses, and Dutch laboratories therefore publish values that barely overlap: UMC Utrecht uses 10.6-16.6 seconds, LUMC 15.3-18.7 seconds and Franciscus Gasthuis 15-22 seconds. A thrombin time of 12 seconds would be normal at one laboratory and low at another. We therefore state no number: read your result against the reference interval of the laboratory that performed the test.
Unit: s
Reference values can vary between laboratories. Discuss your results with your GP for explanation and treatment decisions.
Thrombin Time: what this test measures
This test measures the time for plasma to clot after adding thrombin directly. It bypasses the intrinsic and extrinsic pathways, evaluating only the final fibrinogen to fibrin conversion.
Thrombin Time: why this value matters
TT helps identify fibrinogen abnormalities (dysfibrinogenaemia), detect heparin contamination, and evaluate unexplained prolongation of PT or aPTT.
Thrombin Time: how the blood test works
- Referral
- No GP referral needed. After the order we arrange the referral through ZorgDomein, within one business day; orders after 17:00 or at the weekend start on the next business day. ZorgDomein emails a barcode, and that barcode is what the draw site needs.
- The draw
- A blood draw from a vein in the arm, at a partner laboratory's draw site. No home kit, no finger prick.
- Results
- Turnaround: up to 36 hours after your blood draw (estimate).
- Where
- 650+ draw sites run by independent laboratories across the Netherlands. Draw sites
Thrombin Time: when is testing worthwhile?
TT is ordered when fibrinogen dysfunction is suspected, when heparin contamination needs to be ruled out, or as part of a comprehensive coagulation evaluation.
Thrombin Time: symptoms of a high or low value
Low Levels
A short thrombin time is generally not clinically significant.
High Levels
A prolonged TT may indicate low or dysfunctional fibrinogen, heparin effect, high fibrin degradation products, or paraprotein interference.
Thrombin Time: lifestyle and this value
If fibrinogen abnormalities are identified, your healthcare provider will determine the cause. Maintaining liver health through a balanced diet and moderate alcohol consumption supports normal fibrinogen production.
Thrombin Time: frequently asked questions
When is thrombin time more useful than PT or aPTT?
TT specifically evaluates the final clotting step. It is particularly useful for detecting heparin contamination and diagnosing rare fibrinogen disorders.
What is dysfibrinogenaemia?
A condition where fibrinogen is present in normal amounts but does not function properly. TT can detect this.
Can medications affect thrombin time?
Yes. Heparin, direct thrombin inhibitors (dabigatran), and fibrinolytic agents can all prolong TT.
Results without a doctor's assessment
You receive your values with the unit and reference range. A doctor's assessment is not part of this site. Discuss your results with your GP for explanation and treatment decisions.
Thrombin Time
€16,-