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VON WILLEBRAND DISEASE
von Willebrand Disease
What Is It?
von Willebrand disease is a hereditary deficiency or abnormality of the
von Willebrand factor in the blood, a protein that affects platelet function.
It's the most common hereditary disorder of platelet function, affecting
both women and men. The disease is estimated to occur in 1% to 2% of the
The disease was first described by Erik von Willebrand, a Finnish physician
who reported a new type of bleeding disorder among island people in Sweden
In von Willebrand disease, blood platelets don't stick to holes in blood
vessel walls. Platelets are tiny particles in the blood that clump together
at the site of an injury to prepare for the formation of a blood clot. von
Willebrand factor causes them to bind to areas of a blood vessel that are
damaged. If there is too little von Willebrand factor or the factor is defective,
platelets do not gather properly when a blood vessel is injured.
von Willebrand factor is found in plasma, platelets and blood vessel walls.
When the factor is missing or defective, the first step in plugging a blood
vessel injury (platelets adhere to the vessel wall at the site of the injury)
doesn't take place. As a result, bleeding doesn't stop as quickly as it
should, although it usually stops eventually.
There are no racial or ethnic associations with the disorder. A family history
of a bleeding disorder is the primary risk factor.
Researchers have identified many variations of the disease, but most fall
into the following classifications:
Type I: This is the most common and
mildest form of von Willebrand disease. Levels of von Willebrand factor
are lower than normal, and levels of factor VIII may also be reduced.
Type II: In these people, the von Willebrand
factor itself has an abnormality. Depending on the abnormality, they may
be classified as having Type IIa or Type IIb. In Type IIa, the level of
von Willebrand factor is reduced, as is the ability of platelets to clump
together. In Type IIb, although the factor itself is defective, the ability
of platelets to clump together is actually increased.
Type III: This is severe von Willebrand
disease. These people may have a total absence of von Willebrand factor,
and factor VIII levels are often less than 10%.
Pseudo (or platelet-type) von Willebrand disease:
This disorder resembles Type IIb von Willebrand disease, but the
defects appears to be in the platelets, rather than the von Willebrand factor.
Once in a while, people develop what appears to be von Willebrand disease
later in life. When this occurs in those who have no family history of
disease, it is thought that they're probably producing antibodies that
destroy or decrease the amount of von Willebrand factor. Some other people
have "acquired" a form of the disease in association with another disorder,
such as rheumatoid arthritis, systemic lupus erythematosus, kidney disease
The life span of patients is usually normal length. Since the disease is
genetically transmitted, genetic counseling may be recommended for parents.
von Willebrand disease can be more complicated for women because of obstetric
and gynecological issues.
Like hemophilia, the disease is passed down through the genes. But unlike
hemophilia, which usually affects only males, von Willebrand disease occurs
in men and women equally.
A man or woman with the disease has a 50% chance of passing the gene on
to his or her child. Types I and II are usually inherited in what is known
as a "dominant" pattern. This means that if even one parent has the gene
and passes it to a child, the child gets the disease. Whether the child
has no symptoms, mild symptoms or, less commonly, severe symptoms, he or
she definitely has the disease. Regardless of severity of the symptoms,
the child can still pass the gene to his or her own offspring.
Type III von Willebrand disease, however, is usually inherited in a "recessive" pattern.
This type occurs when the child inherits the gene from both parents. Even
if both parents have mild or asymptomatic disease, their children are
likely to be severely affected.
These patterns of inheritance differ from hemophilia, which is caused by
a defect in one of the "sex-linked" chromosomes. A man with hemophilia
cannot pass the gene on to a son, because the abnormality is carried on
the X chromosome
and a man contributes only a Y chromosome to his male offspring. von Willebrand
disease is found on the autosomal chromosomes and therefore can be inherited
by either males or females.
von Willebrand disease can often be traced through several generations in
a family. Some have symptoms while others just carry the gene.
Symptoms and Diagnosis
Diagnosis can be difficult. When a healthcare practitioner hears of recurrent
nosebleeds, easy bruising, heavy menstrual periods or longer than usual
bleeding after such routine operations as tonsillectomies or tooth extractions,
diagnostic tests should be performed to rule out the possibility of von
Usually, a person with von Willebrand disease has a parent with a history
of bleeding problems. Typically, a child bruises easily or has bleeds excessively
after a skin cut, tooth extraction, tonsillectomy or other surgery. A woman
may have increased menstrual bleeding. Bleeding may worsen at times. On
the other hand, hormonal changes, stress, pregnancy, inflammation and infections
may stimulate the body to increase production of the von Willebrand factor
and temporarily improve clot formation.
Laboratory tests may determine that the number of platelets is normal but
bleeding time is abnormally long. Bleeding time is the amount of time that
elapses before bleeding stops after a small cut is made on the forearm.
To make the diagnosis, doctors may order tests that measure the amount of
von Willebrand factor in the blood. Because the von Willebrand factor is
the protein that carries factor VIII in the blood, the blood level of factor
VIII may also be decreased.
Diagnostic signs can include:
normal platelet count
prolonged bleeding time
reduced von Willebrand factor level
reduced platelet adhesion may occur
reduced or increased platelet aggregation (platelet aggregation test)
ristocetin cofactor is reduced
There are a range of treatment choices that depend on whether the illness
is mild or severe. Many people with von Willebrand disease never even need
Stimate, desmopressin acetate (DDAVP), a drug sprayed into the nose, is
the treatment of choice for mild von Willebrand disease. Bleeding is usually
controlled in individuals with mild von Willebrand disease by using this
nasal spray to boost their own factor VIII and von Willebrand levels. DDAVP
may be given to increase the amount of the von Willebrand factor long enough
for surgery or dental procedures to be performed. DDAVP is a synthetic product
that carries no risk of infectious disease.
For excessive bleeding, infusions of a viral inactivated factor VIII product
rich in von Willebrand factor, such as Humate-P, Alphanate and Koate DVI,
may be required. If trauma occurs or surgery is scheduled, desmopressin
acetate can be given to raise the levels of von Willebrand factor, which
will decrease the tendency toward bleeding. Fresh plasma may also be used
to decrease bleeding but the risk of viral infection can be high.
Children with von Willebrand disease should avoid unnecessary trauma, and
those with severe disease should avoid certain contact sports. During menstruation,
adolescent females may want to take extra precautions to avoid accidents.
During bleeding episodes, they can elevate and apply cold compresses and
gentle pressure to the area. During nosebleeds, they can apply pressure
over the bridge of the nose lean forward to prevent blood running down the
back of the throat and being swallowed.
Aspirin and many of the drugs used for arthritis can aggravate bleeding
because they interfere with platelet function. People who have von Willebrand
disease can take acetaminophen for pain relief because it doesn't inhibit
The National Hemophilia Foundation's Medical and Scientific Advisory Council
(MASAC) made recommendations for treatment of von Willebrand disease in
November of 1999. They include:
Stimate, desmopressin acetate (DDAVP), a nasal spray or injection.
For patients who have become unresponsive to DDAVP or need surgical
procedures, viral-inactivated factor VIII preparations rich in von Willebrand
factor, such as Alphanate, Humate-P and Koate DVI, are recommended.
Cryoprecipitate is not recommended except in life-threatening emergencies
because of the risk of HIV and hepatitis infection. Despite greatly improved
screening and purification for viral inactivation in blood products, cryoprecipitate
can still be infectious.
After any kind of surgery, hemorrhaging may occur. The condition is worsened
by the use of aspirin and other nonsteroidal anti-inflammatory drugs.
Women may have heavy menstrual periods as well as risks during pregnancy
Those who have this disorder and are scheduled for surgery or are in an
accident, should be sure to notify healthcare providers about the condition.
The information contained on the NHF web site is provided for your general
information only. NHF does not give medical advice or engage in the practice
of medicine. NHF under no circumstances recommends particular treatment
for specific individuals and in all cases recommends that you consult your
physician or local treatment center before pursuing any course of treatment.
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