Von Willebrand Factor and Its Role in Hemostasis

Introduction to VWF

Von Willebrand factor (VWF) is a multimeric plasma glycoprotein that mediates platelet adhesion and aggregation at sites of vascular injury, and also carries and stabilizes coagulation factor VIII (FVIII) in the circulation, playing a crucial role in normal hemostasis, as noted by the American Society of Hematology 1, 2

Deficiency or dysfunction of VWF results in von Willebrand disease (VWD), the most common inherited bleeding disorder, affecting approximately 1% of the general population, according to the American College of Medical Genetics 1, 2
VWD can be classified into three main types, with Type 1 being a partial quantitative deficiency, Type 2 being a qualitative deficiency, and Type 3 being a virtually complete quantitative deficiency, as classified by the National Heart, Lung, and Blood Institute 2
The American Academy of Pediatrics notes that VWF levels can vary in response to clinical status as it is an acute phase reactant, and has a relatively short half-life of 8-12 hours after infusion 3

The American Academy of Pediatrics also recommends that diagnosis of VWD can be challenging and may require multiple tests to evaluate the various functions of VWF, and that VWF levels can fluctuate as an acute phase reactant, potentially resulting in falsely elevated results during stress or inflammation 3
Testing may need to be repeated up to 3 times to ensure reliable results, and intracranial hemorrhage (ICH) is extremely rare in VWD, making it an unlikely cause of spontaneous ICH, as stated by the American Academy of Pediatrics 3

von Willebrand factor enables platelets to adhere to exposed collagen at sites of vascular injury, acting as a bridge between platelet GPIb receptors and the subendothelial matrix; this adhesion is especially critical under high‑shear‑stress conditions. 4

von Willebrand factor binds to circulating coagulation Factor VIII and stabilizes it, preventing rapid degradation and thereby preserving normal coagulation activity. 5

The primary platelet receptor for von Willebrand factor is glycoprotein Ib (GPIb), which mediates the initial tethering and adhesion of platelets to the vessel wall; interaction with GpIIb/IIIa is secondary. 6