1179. Von Willebrand Factor

Von Willebrand factor is a plasma glycoprotein involved in the initial stopping of bleeding (primary hemostasis). It promotes platelet adhesion to damaged vascular sites and transports and stabilizes factor VIII, a key protein in the blood coagulation cascade. A decrease in the amount of von Willebrand factor in the blood or a disruption in its activity leads to a tendency to bleed.

This test is used to diagnose von Willebrand disease (pseudohemophilia), thrombotic purpura, and hemolytic anemias. It is best tested in conjunction with a coagulation profile.

Von Willebrand factor is a protein found in the endothelium and platelets, circulates freely in the blood, and:

• promotes platelet adhesion to subendothelial collagen during vascular injury;
• promotes platelet aggregation, stabilizing the initial platelet clot;
• is a carrier and stabilizer of factor VIII, protecting it from proteolytic degradation.

Von Willebrand factor deficiency or defect is the primary cause of von Willebrand disease, the most common inherited bleeding disorder.

When?

• If von Willebrand disease is suspected.
• To diagnose von Willebrand disease and determine its type.
• For screening before elective surgeries.
• For bleeding disorders of unknown etiology.

Who?

Patients with a personal or family history of severe, prolonged, and/or spontaneous bleeding:

• nosebleeds, bleeding gums after dental procedures;
• bruising after minor blows or injuries;
• heavy and/or prolonged menstrual bleeding in women;
• blood in urine or stool;
• prolonged bleeding after surgery.

• Venous blood

In order to exclude factors that may affect the test results, we recommend to follow the preparation rules: