Thrombin generation assay

A thrombin generation assay or thrombin generation test is a global coagulation assay and type of coagulation test which can be used to assess coagulation and thrombotic risk. It is based on the potential of a plasma to generate thrombin over time, following activation of coagulation via addition of phospholipids, tissue factor, and calcium. The results of the TGA can be output as a thrombogram or thrombin generation curve using computer software with calculation of thrombogram parameters.
TGAs can be performed with methods like the semi-automated calibrated automated thrombogram or the fully automated ST Genesia system. TGAs were first used as manual assays in the 1950s and have since become increasingly automated.

Parameters

Thrombogram parameters for the TGA include:

Lag time
Time to peak or ttPeak
Start tail
Peak height or peak thrombin
Velocity index
Endogenous thrombin potential
ETP-based APC resistance test

The addition of activated protein C to a TGA results in an inhibition of thrombin generation as measured by reduction of the endogenous thrombin potential. This can be used to assess APC resistance and is termed the ETP-based APC resistance test. Results may be expressed as normalized APC sensitivity ratio, which corresponds to the ratio of the ETP measured in the presence and absence of APC divided by the same ratio in reference plasma. The higher the nAPCsr value, the greater the APC resistance of the person. The ETP-based APC resistance test was developed in 1997.