Which factor is often decreased in patients with von Willebrand's disease?

Von Willebrand's disease is a genetic disorder that affects blood clotting due to a deficiency or dysfunction of von Willebrand factor (vWF), which plays a crucial role in hemostasis. This factor helps platelets adhere to the sites of vascular injury and also stabilizes factor VIII in circulation.

In patients with von Willebrand's disease, one of the key changes observed is a decrease in factor VIII levels. This occurs because von Willebrand factor is essential for the protection of factor VIII from degradation in the bloodstream; when vWF is deficient or dysfunctional, factor VIII is not adequately stabilized. As a result, the half-life of factor VIII in circulation is significantly reduced, leading to lower levels of this coagulation factor.

Understanding the relationship between von Willebrand factor and factor VIII is critical for diagnosing and managing von Willebrand's disease, as it directly impacts the coagulation cascade and the patient’s bleeding risk. Thus, the decrease in factor VIII is a hallmark characteristic of this condition.