Dysfunctional Hemostasis

This book chapter provides an overview of hemostasis, with a focus on dysfunctional hemostasis. Hemostasis is a cascade of processes that occur in response to tissue damage to form a clot and prevent excessive bleeding. Primary hemostasis involves platelet activation and the formation of a loosely bound platelet plug. Secondary hemostasis strengthens the platelet plug through the conversion of fibrinogen to fibrin. The intrinsic and extrinsic pathways of the coagulation cascade are discussed, along with the important role of vitamin K in the synthesis of coagulation factors. Evaluation of hemostasis through various tests, such as activated partial thromboplastin time (aPTT) and prothrombin time (PT), is also explored. The chapter concludes with an overview of platelet function testing using light transmission aggregometry and the VerifyNow-P2Y12 assay.