What is von Willebrand factor activity?

What is von Willebrand factor activity?

A von Willebrand factor (vWF) activity – ristocetin (riss-teh-SEE-tin) cofactor test lets doctors see how a protein called von Willebrand factor is working. The body’s clotting factors work together in a special order, almost like pieces of a puzzle. When the last piece is in place, the clot develops.

Is von Willebrand factor a protein?

Von Willebrand disease (VWD) is a blood disorder in which the blood does not clot properly. Blood contains many proteins that help the blood clot when needed. One of these proteins is called von Willebrand factor (VWF).

What is VWF ristocetin cofactor?

The Von Willebrand Ristocetin Cofactor [vWF:RCo] assay measures the ability of a plasma sample to agglutinate platelets in the presence of the antibiotic Ristocetin. The rate of Ristocetin induced agglutination is related to the concentration and functional activity of the plasma von Willebrand factor.

What does low von Willebrand factor activity mean?

Facts about low VWF: It is a category for people with somewhat low VWF levels (between 30 and 50%) who have increased bleeding and bruising symptoms. VWF can be low because there is a problem with how it is made and released from cells or may be related to blood type.

What does high VWF mean?

VWF is an acute-phase reactant and may be elevated above baseline in association with a variety of conditions including inflammation, stress, exercise, liver disease, pregnancy or estrogen therapy. Baseline VWF levels also increase with aging.

What does it mean if factor VIII is high?

If your levels of factor VIII are too high, you are likely at a higher risk for thrombosis, which is blood clot formation in your blood vessels. In this case, your doctor may perform additional tests or prescribe anticoagulant therapy.

Is VWF a coagulation factor?

VWF plays a major role in blood coagulation. Therefore, VWF deficiency or dysfunction (von Willebrand disease) leads to a bleeding tendency, which is most apparent in tissues having high blood flow shear in narrow vessels.

What chromosome is VWF on?

The human vWF gene has been localized to the short arm of chromosome 12 (12p12-7pter).

What is the Ristocetin test used for?

Ristocetin-induced platelet aggregation (RIPA) is used as an in vitro test to determine the presence and integrity of the platelet glycoprotein (GP) Ibα-V-IX complex and von Willebrand factor (VWF) interaction and is usually performed using platelet-rich plasma (PRP).

How do you test for VWF?

The blood tests that a doctor can order to diagnose VWD (or another platelet disorder) include:

1. Factor VIII clotting activity―To measure the amount of factor VIII in the blood.
2. Von Willebrand factor antigen―To measure the amount of VWF in the blood.

What is normal range of VWF?

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. The 5 percent of persons with VWF levels of less than 50 IU per dL include those with VWD and those with slightly low, but nondiagnostic, levels.

What causes elevated Factor VII levels?

Factor VII is increased in the following: Oral contraceptive use and pregnancy. An increase in factor VII has been associated with thrombophilia.