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Von Willebrand disease

Von Willebrand's disease (vWD) is the most common hereditary coagulation abnormality described in humans. It arises from a qualitative or quantitative deficiency of von Willebrand factor (vWF), a multimeric protein that is required for platelet adhesion. It is known to affect humans and, in veterinary medicine, dogs. more...

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Symptoms

The various types of vWD present with varying degrees of bleeding tendency. Severe internal or joint bleeding is rare (only in type 3 vWD); bruising, nosebleeds, heavy menstrual periods (in women) and blood loss during childbirth (rare) may occur.

Diagnosis

When suspected, blood plasma of a patient needs to be investigated for quantitative and qualitative deficiencies of vWF. This is achieved by measuring the amount of vWF in a vWF antigen assay and the functionallity of vWF with a glycoprotein (GP)Ib binding assay, a collagen binding assay or, a ristocetin cofactor (RiCof) activity assay. Factor VIII levels are also performed as factor VIII is bound to vWF which protects the factor VIII from rapid break down within the blood. Deficiency of vWF can therefore lead to a reduction in Factor VIII levels. Normal levels do not exclude all forms of vWD: particularly type 2 which may only be revealed by investigating platelet interaction with subendothelium under flow (PAF), a highly specialistic coagulation study not routinely performed in most medical laboratories. A platelet aggregation assay will show an abnormal response to ristocetin with normal responses to the other agonists used. A platelet function assay (PFA) will give an abnormal collagen/adrenaline closure time but a normal collagen/ADP time. Type 2N can only be diagnosed by performing a "factor VIII binding" assay. Detection of vWD is complicated by vWF being an acute phase reactant with levels rising in infection, pregnancy and stress.

Other tests performed in any patient with bleeding problems are a full blood count (especially platelet counts), APTT (activated partial thromboplastin time), prothrombin time, thrombin time and fibrinogen level. Testing for factor IX may also be performed if hemophilia B is suspected. Other coagulation factor assays may be performed depending on the results of a coagulation screen.

Classification and types

Read more at Wikipedia.org


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Von Willebrand's disease underdiagnosed in women
From AORN Journal, 1/1/04

Most women with von Willebrand's disease, a common bleeding disorder that affects up to 5% of the population, are not diagnosed or treated, according to a recent Harris Interactive survey. The disease is genetic, can affect both women and men, and is caused by a deficiency of the von Willebrand factor, a blood clotting protein.

Symptoms of the disease include heavy and prolonged menstrual bleeding, prolonged and frequent nosebleeds, easy bruising, and bleeding during tooth brushing or after dental surgery. Many women report symptoms related to menstruation, including

* having periods that Last more than seven days (ie, 10% of women aged 18 to 45 who have menstrual periods),

* having heavy menstrual flow (ie, 33% of women who have periods), and

* bleeding through a tampon or sanitary napkin in an hour or Less (ie, 48% of women aged 18 to 45).

There are several reasons for the misdiagnosis of von Willebrand's disease or dismissal of its symptoms. Many physicians are unfamiliar with the disease, and heavy menstrual bleeding often is considered a gynecologic rather than hematologic problem. Many people have the misconception that bleeding disorders only affect men. Other causes for misdiagnosis include tests producing false-negative results, symptoms being masked by hormonal changes, and women with a family history of bleeding disorders ignoring the symptoms.

More than half of the women surveyed said they or someone they know had sought treatment from a physician for heavy menstrual bleeding--but none of these women were diagnosed with von Willebrand's disease. The top diagnoses were

* fibroids (25%),

* endometriosis (21%),

* hormonal imbalance (17%),

* no diagnosis (17%),

* polyps (8%), and

* cancer (3%).

According to the survey report, the Centers for Disease Control and Prevention believes 5% of hysterectomies are performed because of excessive uterine bleeding that may be caused by von Willebrand's disease.

This survey was conducted online in August 2003. A nationwide cross section of more than 1,000 women age 18 to 45 participated.

"Hereditary Needing disorder--von Willebrand Disease--seems to be widely underdiagnosed and undertreated," Health Care News 3 (Nov 24, 2003).

COPYRIGHT 2004 Association of Operating Room Nurses, Inc.
COPYRIGHT 2004 Gale Group

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