Registered Cardiovascular Invasive Specialist (RCIS) Practice Test

What is the primary function of thrombin in the coagulation process?

1. To activate factor X

2. To convert fibrinogen to fibrin

3. To degrade fibrin

4. To enhance platelet aggregation

The correct answer is: To convert fibrinogen to fibrin

Thrombin plays a crucial role in the coagulation process primarily by converting fibrinogen, a soluble plasma glycoprotein, into fibrin, an insoluble protein that forms the structural basis of a blood clot. When there is vascular injury, thrombin is generated from prothrombin through the action of activated factor X and factor V in the prothrombinase complex. Thrombin's ability to convert fibrinogen into fibrin is essential for clot formation, as it leads to the stabilization of the platelet plug and helps to prevent excessive bleeding. While thrombin has other functions, such as enhancing platelet aggregation and promoting the activation of several coagulation factors, its primary and most critical function is the conversion of fibrinogen to fibrin. This transformation is key to the final stages of the coagulation cascade and is what ultimately leads to the formation of a stable blood clot.