Von Willebrand disease (VWD) is the most common congenital bleeding disorder affecting 0.1- 3 percent of the population. It is a bleeding disorder that arises from decreased amounts of or abnormalities in von Willebrand factor (VWF) protein. This protein has two functions important in helping blood clot. VWF binds to circulating factor VIII, protecting it from breaking down, and VWF is the "glue" that attaches platelets to the blood vessel wall at the site of an injury. VWD arises from genetic mutations that cause a reduced level or an abnormal version of VWF. VWD affects men and women in equally and is generally characterized by bleeding in the nose or mouth.

There are three major types of VWD. Types 1 (accounts for more than 70 percent of cases) and 3 refer to mild and severe quantitative deficiency of VWF respectively, whereas type 2 refers to qualitative abnormalities. Type 2 is further divided into four subtypes (A, B, M, N).

Inheritance

The presence of VWD is determined by a gene carried on chromosome 12. VWD occurs equally among male and females. Occasionally, the abnormal gene may appear for the first time in a patient when neither parent has the abnormality. This is called a new mutation, and the disorder could then be passed on to subsequent children. If the family history reveals one parent with bleeding symptoms, then approximately 50 percent of the offspring will be affected.

Types of bleeds

The most common bleeding episodes in VWD include excessive bleeding from the skin, mucous membranes (mouth, gastrointestinal tract), and nose. Women with VWD can have heavy menstrual periods. Prolonged bleeding or bruising after trauma to skin or mucous membranes is characteristic of VWD, as is prolonged oral bleeding after tooth eruption or with biting the tongue or lips. Those with the disorder may have heavy bleeding following tooth extraction or other oral surgery such as tonsillectomy. There may also be a family history of mucous membrane bleeding- a sister, aunt or mother who has heavy periods or nosebleeds, or a father who has nosebleeds and has bled excessively after surgical procedures.

Diagnosis

Diagnostic testing can yield varying results; so, people may need to be tested several times before a diagnosis is established. Individual patients may experience considerable variability over time, because the level of VWF in the bloodstream may increase under certain conditions, such as pregnancy, stress and hyperthyroidism. The use of oral contraceptives, pregnancy, estrogen-replacement therapy and exercise may also alter laboratory test results. Additionally, levels of VWF can be influenced by a person’s blood type (those with type AB have an average of 60- 70 percent higher levels than do those with type O blood).

Treatment of bleeding

A range of treatment choices is available and depends on the type and severity of VWD. Treatment with some type of medication is generally necessary for all surgeries and invasive procedures, including dental work (except cleanings), suturing and significant trauma with subsequent bleeding especially involving head, neck and abdominal injuries.

DDAVP (desmopressin acetate) is a synthetic form of a natural hormone and is known to stimulate the cells inside blood vessels to release additional VWF, Factor VIIII. DDAVP typically results in a two to threefold increase in VWF and Factor VIII. It is given as an intravenous infusion or as a nasal spray (Stimate). DDAVP is effective for most people with type 1 or 2A VWD. DDAVP is preferred as a treatment over plasma products when it is effective because it does not carry the risk of virus transmission and is generally less expensive.

Humate P (ZLB Behring), Koate HP (Bayer) and Alphanate-SD/HT (Alpha Therapeutics) are all plasma-derived clotting factor concentrates that contain VWF, and Humate P has FDA approval for the treatment of VWD. These products are very effective in raising VWF and factor VIII levels.

Portions of this material were reprinted with permission from the Nurses Guide to Bleeding Disorders, published by the National Hemophilia Foundation.