Von Willebrand Factor
(VWF)

Is a blood glycoprotein involved in hemostasis, specifically, platelet adhesion.

Sample type:

A blood sample drawn from a vein in your arm collected in a blue-top tube

Uses:

Used to investigate excessive or recurrent bleeding episodes or a personal or family history of excessive bleeding. Testing is used to help diagnose von Willebrand disease (VWD) and distinguish between the various types of VWD.

- Precautions:

1) Some drugs like warfarin and other oral anticoagulants decrease the value.

2) Avoid the excessive agitation of the blood.

3) Avoid prolonged use of a tourniquet.

- Interfering factors:

A variety of clinical disorders, including pregnancy, inflammatory disease, and use of oral contraceptives, also can cause increased levels of VWF.3,4 Transient elevations in VWF levels could mask actual low or borderline levels.

- Pre analytical errors:

i. Sample collection

ii. Collection tubes

iii. Sample delivery to the laboratory

- Corrective action:

Stopping the blood from vessels (hemostasis) following vascular injury. Works by mediating the adherence of platelets to one another and to sites of vascular damage.

- Post analytical errors:

i. Release of the laboratory test report

ii. Reporting of test results

iii. Sample storage and disposal

- reference range:

In the general population, the mean level of plasma VWF is 100 IU per dL, with a normal reference range between 50 and 200 IU per dL.