von Willebrand's and PTT

[Kluver_Bucy]

Why would von Willebrand's disease have an increase in PTT but not PT? Does anyone know. The increase in bleeding time is straight forward, but this concept is confusing.

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[bizcuit241]

von Willebrand is associated with factor VIII (the two travel together). von Willebrand disease causes a functional loss of factor VIII which is measured by PTT and not PT.

 

[double elle]

Unless you have a mixed coagulopathy of some sort, I always remember that the PT will be off (INR) if the VIT K dependent factors are off...2, 7, 9, 10, C, S...

PTT is the INTRINSIC pathway because it has an EXTRA T INSIDE the name.

 

[HiddenTruth]

Unless you have a mixed coagulopathy of some sort, I always remember that the PT will be off (INR) if the VIT K dependent factors are off...2, 7, 9, 10, C, S...

BOTH PT and PTT are affected with warfarin.

 

[12R34Y]

Why would von Willebrand's disease have an increase in PTT but not PT? Does anyone know. The increase in bleeding time is straight forward, but this concept is confusing.

VWF prolongs the half-life of F8. therefore if you have decreased VWF you have decreased F8 and thus a prolonged PTT.

later