What Is von Willebrand Disease?

Von Willebrand disease (VWD) is a bleeding disorder. It affects your blood's ability to clot. If your blood doesn't clot, you can have heavy, hard-to-stop bleeding after an injury. The bleeding can damage your internal organs or even cause death, although this is rare.

In VWD, you either have low levels of a certain protein in your blood, or the protein doesn't work the way it should. The protein is called von Willebrand factor, and it helps the blood clot.

Normally, when one of your blood vessels is injured, you start to bleed. Small blood cell fragments called platelets (PLATE-lets) clump together to plug the hole in the blood vessel and stop the bleeding. Von Willebrand factor acts like glue to help the platelets stick together and form a blood clot.

Von Willebrand factor also carries clotting factor VIII (8), another important protein that helps your blood clot. Factor VIII is the protein that's inactive or missing in people who have hemophilia, another clotting disorder.

VWD is more common and usually milder than hemophilia. In fact, VWD is the most common of all the inherited bleeding disorders. It occurs in about 1 out of every 100 to 1,000 people. VWD affects both males and females, while hemophilia mainly affects males.