You are tending to a patient with a high tendency to bleeding. He bruises easily and has bleeding from his gums. Analysis of coagulation factors in his blood shows normal levels of factor V but low levels of factor VIII. Injection of factor VIII provides only minimal benefit and you find that the injected protein is rapidly degraded. Using a platelet aggregation test you find that combination of your patients serum with normal platelets results in only 20% of the platelet aggregation seen with both samples from a normal individual. Based on these findings you determine that your patient is deficient in which of the following factors of coagulation?

Question

Quizplus · Accepted Answer

The symptoms and test results suggest a deficiency in von Willebrand factor, which is necessary for platelet adhesion and stabilization of factor VIII. von Willebrand disease (vWD) results from defects in von Willebrand factor (vWF). The disorder is characterized by bleeding from mucocutaneous sites (typical skin and mucous membranes) rather than from deep tissues and joints. vWF is involved in two important reactions of blood coagulation. The first is the interaction of vWF with specific receptors on the surface of platelets and the subendothelial connective tissue. This interaction allows platelets to adhere to areas of vascular injury. The second role of vWF is to bind to and stabilize factor VIII allowing factor VIII to survive in the blood. As a consequence of these roles for vWF, deficiencies result in defective platelet adhesion and to secondary deficiencies in factor VIII. Since factor VIII deficiency results in hemophilia A, vWF deficiencies can manifest with clinical symptoms that appear to be hemophilia A.

You Are Tending to a Patient with a High Tendency