Browse Medical Laboratory Calculators
Thrombin Time (TT) Converter
Thrombin Time (TT), also known as Thrombin Clotting Time (TCT), measures the time it takes for a clot to form in the plasma of a blood sample containing anticoagulant, after an excess of thrombin has been added.
It assesses the final step of the coagulation cascade (conversion of fibrinogen to fibrin). While results are reported in seconds, converting this value to a Ratio (Patient/Control) is often required for standardization across different reagents and laboratories.
Patient Result
SecondsRaw clotting time in seconds.
Standardized
Patient Time ÷ Control Time.
Clinical Context
Reference Ranges:
• Seconds: Typically 12 – 19 seconds (highly reagent dependent).
• Ratio: Typically < 1.2 or 1.3.
Prolonged TT Causes:
• Contamination: Presence of Heparin (most common) or Direct Thrombin Inhibitors (Dabigatran, Argatroban).
• Fibrinogen Issues: Hypofibrinogenemia (low levels) or Dysfibrinogenemia (dysfunctional protein).
• FDPs: High levels of Fibrin Degradation Products (e.g., in DIC).
Clinical References
How to Use This Converter
Follow these steps to calculate the Thrombin Time Ratio.
Set Control
Enter the Control Time (in seconds) for your laboratory’s specific reagent lot. The default is 15.0 seconds.
Enter Patient Result
Input the patient’s Thrombin Time in the Time (sec) field.
Automatic Calculation
The tool instantly calculates the TT Ratio. You can also enter a ratio to reverse-calculate the estimated seconds.
Reset
Use the Clear button to reset all fields, including the control.
Frequently Asked Questions
Yes. PT measures the extrinsic pathway (Factors VII, X, V, II, I). TT specifically measures the conversion of Fibrinogen to Fibrin (Factor I to Ia).
No. Warfarin affects Vitamin K dependent factors. TT measures fibrinogen function and is usually normal in patients on Warfarin.