Which laboratory finding is classically associated with von Willebrand disease?

Which laboratory finding is classically associated with von Willebrand disease?

• A. Prolonged PT.
• B. Prolonged partial thromboplastin time is isolated.
• C. Thrombocytopenia.
• D. Isolated prolonged partial thromboplastin time.

Answer: (D)

Von Willebrand disease shows a problem with primary hemostasis due to deficient or dysfunctional von Willebrand factor, which also stabilizes factor VIII. Because the extrinsic pathway is unaffected and platelet numbers are usually normal, the typical lab pattern is a normal PT and a prolonged PTT caused by reduced factor VIII activity. This creates the picture of an isolated prolonged partial thromboplastin time. A prolonged PT would suggest an extrinsic pathway issue, which is not characteristic of VWD, and thrombocytopenia would imply a low platelet count rather than a platelet adhesion defect.

Von Willebrand disease shows a problem with primary hemostasis due to deficient or dysfunctional von Willebrand factor, which also stabilizes factor VIII. Because the extrinsic pathway is unaffected and platelet numbers are usually normal, the typical lab pattern is a normal PT and a prolonged PTT caused by reduced factor VIII activity. This creates the picture of an isolated prolonged partial thromboplastin time. A prolonged PT would suggest an extrinsic pathway issue, which is not characteristic of VWD, and thrombocytopenia would imply a low platelet count rather than a platelet adhesion defect.