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VON WILLEBRAND DISEASE
An Introduction to the Basics
Complete
on-line presentation 1 CEU Credit
AHF®, INC. The Hemophilia Disease Management Company
provides a full line of clotting medications, supplies, and ancillaries to
families who are on home infusion programs. Bleeding disorders are
our only business and we have provided uninterrupted services to
families and medical institutions since 1989.
AHF sponsors this presentation
to improve services to individuals and families living with bleeding
disorders. One CEU (Continuing Education Unit) is available from
CCMC
(Commission for Case Managers Certification) for this course. In order to obtain credit, you will need to read
the attached course presentation and then complete the CEU evaluation. The completed
evaluation form will need to be returned to the address indicated below.
vWd
Von Willebrand disease (vWd) is characterized by the inability of the blood to clot
normally. Blood is a fluid carried through the body in tubes called arteries, veins, and
capillaries. When a tube is injured, a small hole forms, letting blood flow out. Stopping
the flow of blood, or clotting, is necessary.
Blood clotting is a process that requires the following three steps to be successful.
- Vasoconstriction - the blood vessel narrows and slows the passage of blood from the hole
- Plug - platelets rush to the site, stick together, and act as a sticky cap or plug to
stop the blood flowing when von Willebrand factor (vWf) is missing from a
persons blood, the clotting problem starts here
- Clot - clotting factors and proteins in the blood, stop at the site, form a solid fibrin
clot, and seal the hole, stopping the flow blood
If any of these steps is missed or does not work correctly, no clot is formed. The
missing, defective, or poorly working element in vWd is a protein called vWf. VWf is a
substance made by the lining cells of the blood vessels. VWf acts as a
"catchers mitt" to bind platelets to the internal site of the "hole
in the vessel" creating a plug.
A person with vWd may experience the inability to form a platelet plug from several
kinds of events. Such events may include bleeding from injury, surgery, or from a
spontaneous bleed. VWf also carries and protects Factor VIII (FVIII). Lack of FVIII will
additionally cause a disruption in the entire clotting chain (cascade) making clot
formation slow or unlikely. Without medical treatment to promote and sustain clotting,
internal bleeding may continue and may cause long-term damage.
VWd occurs in 1 3% of the US population.
VWd is an equal opportunity disorder equally affecting women and men.
This means that approximately 2.6 million persons in the US have vWd.
The Inheritance of vWd
The transmitter for vWd is on a non-sex linked chromosome. This means that a child of
one gender is just as likely to receive this gene as a child of the other gender. vWd is
transmitted when either parent passes on an altered gene to an unborn child. vWd is
inherited in an autosomal dominant mode. This means that a parent who has vWd has a 50%
chance of passing it to each child. If both parents are symptomatic for vWd, they have a
25% chance of having an affected child, a 50% chance of having a child who is a carrier,
and 25% chance of having a child unaffected by vWd.
Some cases of vWd result from a spontaneous mutation during prenatal development. These
individuals will then go on to carry the disorder to future generations. In rare cases,
vWd is acquired during childbirth, drug-therapy, or autoimmune diseases such as rheumatoid
arthritis, types of kidney failure, or certain cancers. Levels of severity range from low
to moderate to severe.
Levels of severity are usually the same within a family, but in rare cases, may vary
from one family member to another.
The Symptoms of vWd
Recurrent nose bleeds
Easy bruising
Heavy or prolonged menstrual flow
Bleeding from digestive or urinary tract
Unusual or excessive bleeding from mouth or gums
Unusual bleeding after surgery, dental procedures, and injury
Bleeds into joints, muscles, or the brain, though less common
Recurrent spontaneous bleeding anywhere, though less common
Testing for vWd to Measure Levels, Function, Severity, and Type
Levels can be mild, moderate, or severe.
Types include type 1 (comprising 70 80% of cases), type 2, and type 3 (rare and
severe).
Type 1 is characterized by decreased vWf activity.
Type 2 is characterized by abnormal vWf.
Type 3 is characterized by no vWf at all.
Specialized labs are necessary, and many community labs are not equipped, to undertake
diagnostic tests for vWd.
Diagnostic testing includes:
Bleeding Time minutes needed to stop a bleed from a small laceration made in the
skin
Factor VIII: C measures amount of factor VIII activity
VWf Antigen measures amount of vWf
Ristocetin Cofactor Activity measures vWf function
VWf Multimers measures the structure of the vWf molecule
Platelet Function Tests measures how well platelets work in the test tube
Test results are often not accurate. Tests may need to be repeated several times, over
months, before a precise diagnosis can be confirmed. Test results may be affected by many
variables in the patient as well as the lab technician.
Results of diagnostic tests may be influenced by:
Menstrual cycle
Use of aspirin or non-steroidal anti-inflammatories
Cold environment
Birth control pills, hormone therapy, pregnancy, breast feeding, and childbirth
Exercise, stress, and crying
Diagnosis of vWd
Diagnosis can be at birth (in families suspecting vWd). Diagnosis may also follow
severe bleeding from accident, dental work, sports injury, or trauma. OBGYNs treating
heavy menstrual bleeding or assessing excessive bleeding with childbirth may make a
diagnosis of vWd.
Common Misdiagnoses and Possible Results
Medical practitioners may fail to consider a bleeding disorder as an explanation when
treating a symptomatic female patient. Some may be unfamiliar with bleeding disorders,
unaware of available diagnostic tests, or deem tests unnecessary. Bleeding symptoms may be
thought to be a result of other causes, for example:
A low platelet count may be considered the result of leukemia, autoimmunity, or other
conditions.
Heavy menstrual bleeding may be seen as hormonal or gynecological.
Surgical solutions, such as hysterectomy, may be carried out unnecessarily as a result
of misdiagnosis of a bleeding disorder.
Bleeding may persist and yet remain undiagnosed, presenting a risk of death in
traumatic situations.
Treatment for vWd
Mild bleeds may be treated with pressure. Often mild bleeds are self-limiting.
Commonly used medications for more severe bleeding include:
Hormones found in oral contraceptives administered intravenously, orally, topically, or
by patch application can often be helpful in prevent bleeding.
Localized bleeding in the nose or mouth may be treated at the site with
Thrombinar, Avitene, or Instat followed by a medication such as Amicar
(aminocaprioc acid).
For more severe bleeds, DDAVP, a synthetic hormone that causes the body to release its
own stores of vWf and FVIII, is successful in treating type 1. (Intravenous injection or
nasal spray administers DDAVP.) Intermediate purity FVIII products can be used for vWf
type 2 and 3 by intravenous injection. This acts as a replacement for the missing protein.
Recombinant and monoclonal FVIII products do not contain any vWf and cannot be used.
Although not a treatment, pregnancy may increase estrogen and, thereby, decrease the
impact of vWd.
AHF does not engage in the practice of medicine. Under no
circumstance does AHF
recommend a particular treatment or medication for a particular individual. In all cases,
AHF recommends that a patient consult a physician or hemophilia treatment center before
beginning a specific treatment.
Setting
the Standard of Care for People with Bleeding Disorders
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VON WILLEBRAND DISEASE - INTRODUCTION TO THE BASICS
- 1 CEU
EVALUATION
It has been our pleasure to share our knowledge and understanding of von Willebrand
disease. We ask that you please take a moment to complete the questions below by checking
"yes" or "no" after each question. Your comments are very valuable to
us. This evaluation is required by CCMC to fulfill CEU obligations. Please print out this
form and return it to AHF, Inc., 31 Moody Road, P.O.B 985, Enfield, CT 06083. Thank you very
much for your cooperation.
YES /NO
1. Did you find the overview informative? ___ ___
Comments:
2. Was the inheritance of vWd explained? ___ ___
Comments:
3. Were the symptoms of vWd explained? ___ ___
Comments:
4. Were the diagnostic tests for vWd explained? ___ ___
Comments:
5. Did the information explain
the treatments for vWd? ___ ___
Comments:
6. Did the information meet your expectations? ___ ___
Comments:
7. Were your questions and concerns addressed? ___ ___
Comments:
Name ___________________________
Institution _________________________
Specialty __________________________
Address ___________________________________________________
Phone and e-mail address _____________________________________
AHF®, Inc. does not prescribe medications or give
medical recommendations to individuals. AHF does not endorse or refer any
particular individual to a specific HTC or medical provider. It is
best to obtain medical recommendations from your physician and/or your HTC.
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