The thrombin time (TC; synonyms: plasma thrombin time, plasma thrombin time; PTZ; thrombin clotting time (TCT), thrombin time, TT) occupies a special position in coagulation diagnostics. It measures the last step in the coagulation cascade, namely fibrin polymerization (process of fibrin stabilization).
Thrombin time measures the conversion of fibrinogen (factor I) to fibrin by addition of thrombin (factor IIa) to the test plasma (= thrombin-induced fibrin formation).
The procedure
Material needed
- Citrate plasma
Preparation of the patient
- Not necessary
Disruptive factors
- None known
Normal value
| 15 – 35 sec. (laboratory dependent) |
Indications
- Fibrin polymerization disorders (dysfibrinogenemia, fibrin(ogen) cleavage products).
- Fibrinogen deficiency
- Heparin or hirudin therapy
- Consumptive coagulopathy
- Checking factors V, X, XIII, prothrombin, fibrinogen.
Interpretation
Interpretation of increased values
- Fibrinogen deficiency:
- Congenital and acquired dysfibrinogenemia (abnormal fibrinogen molecules).
- Newborns in the first weeks of life (due to a fetal blood fibrinogen that is not fully functional).
- Afibrinogenemias (complete absence of fibrinogen in the blood).
- Hypofibrinogenemias (reduced fibrinogen content of the blood).
- Consumption coagulopathy(life-threatening condition in which clotting factors are consumed due to a strong blood clotting process, resulting in a strong bleeding tendency).
- Fibrinolytic therapy (fibrinogen cleavage products).
- Hyperfibrinolysis (increased fibrinolysis/fibrin cleavage).
- Medications:
Interpretation of decreased values
- Not relevant
Other notes
- Thrombin time is not suitable for preoperative diagnosis to detect bleeding tendency.
- Prolonged thrombin time in the presence of normal thromboplastin time (TPZ; English prothrombin time, PT; Quick value) and platelet count and normal or slightly prolonged partial thromboplastin time (PTT) suggests the presence of heparin in plasma.
