Von Willebrand Disease

von Willebrand disease (VWD) is a relatively common, but often missed blood disorder in which the blood fails to clot properly. This defective blood clotting is caused by an insufficient level of a clotting factor in the blood called von Willebrand factor (VWF). In normal circumstances, a blood clot is formed when VWF binds to factor VIII, another clotting protein, and platelets in blood vessel walls. This process results in the formation of a platelet plug during the clotting process. When there is not enough VWF, patients are unable to form such a platelet plug, or it takes longer to do so. As a result, they bleed longer than normal. There are 3 main subtypes of inherited VWD: Type 1 patients have a lower-than-normal level of VWF, type 2 patients have an abnormality in the function of VWF and type 3 patients have a total absence of the clotting factor.

In a proportion of patients, the VWD is acquired as an auto-immune disease, often occurring with an underlying disease, such as certain cancers, autoimmune disorders, or cardiovascular diseases.

The diagnosis of VWD requires a combination of blood tests. This includes a VWF antigen test, which measures the amount of VWF in the blood, tests that measure the time it takes to form a blood clot and tests that measure the platelet function. Of note, some of these tests may have to be repeated before a diagnosis can be made. The main reason for this is that levels of VWF can change over time due to external factors, such as stress, exercise, the use of birth control pills, pregnancy, etc.

The treatment for VWD depends on the type and severity of the bleeding episodes. For patients with a mild form of the disease, simply applying pressure on the wound for a few minutes is often enough to stop the bleed. However, for patients with more severe VWD, a more dedicated therapy may be needed.

One of the more commonly used treatments for VWD consist of injectable desmopressin, a synthetic hormone that stimulates the body to release VWF. In addition to this, anti-fibrinolytic medication (e.g., tranexamic acid) can be given to slow down the breakdown of blood clots, while oral contraceptives can help to control heavy menstrual bleeding.

Finally, more severe forms of VWD are treated with factor replacement therapy. These infusions are either plasma-derived (i.e., made from human blood products) or recombinant (i.e., created in a lab) and contain high levels of VWF and factor VIII. Of note, replacement therapy can also be used prior to surgery in patients with VWD. If the VWD is acquired, antibodies against the VWF exist and recombinant factors can be destroyed by the immune system. These patients can be treated with immune suppressants and recombinant factor 7 (VII).