Von Willebrand disease
Von Willebrand disease, or vWD, is an inherited bleeding disorder - meaning it's passed from parent to child through genes - that affects the blood's ability to clot properly. It takes its name from Dr. Erik von Willebrand, who first described the condition in 1926. As a group, bleeding disorders (hemophilia) are rare. Von Willebrand disease is the most common inherited bleeding disorder, affecting about 1% to 2% of people. Unlike hemophilia, which usually affects only guys, vWD affects both guys and girls.
Normally, bleeding usually occurs when a blood vessel is cut or torn. Platelets (small cells that float in the blood) plug the hole in the blood vessel to stop blood from leaking out. With the help of calcium, vitamin K, and a protein called fibrinogen, the platelets create a mesh to hold the plug in place and close the wound. As this mesh dries, it hardens and forms a scab to protect the wound as it heals.
A substance in the blood known as von Willebrand factor helps platelets stick to damaged blood vessels. Special proteins known as clotting factors are also needed to help blood clot. Von Willebrand factor carries one of these clotting factors, called factor VIII, in the blood.
People with von Willebrand disease have bleeding problems because the levels or function of these blood components needed for clotting are abnormal.
Children born with this disease have one or both of the following:
- The protein does not work as it should.
This clotting protein is called von Willebrand factor. When some of this factor is missing or defective it can cause prolonged bleeding after an injury or accident.
An injury (like a cut) to a blood vessel causes a complex chain of events called the clotting process, which results in a blood clot. Clotting is your body's reaction to bleeding to keep you from losing too much blood. Losing too much blood can be life threatening and can damage your internal organs. When a blood vessel is damaged, there are four stages in the normal formation of a clot.
Stage 1: The blood vessel is damaged and the bleeding starts.
Stage 2: The blood vessels constrict to slow the flow of blood to the injured area.
Stage 3: Platelets stick to, and spread on, the walls of damaged blood vessels. This is called platelet adhesion. These spreading platelets release substances that activate other nearby platelets which then clump together at the site of injury to form a platelet plug. This is called platelet aggregation.
Stage 4: The surface of these activated platelets then provides a surface on which blood clotting can occur. Clotting proteins circulating in the blood are activated on the surface of the platelets to form a mesh-like fibrin clot.(reference: Canadian Hemophilia Society)
von Willebrand Factor
Certain proteins in your blood help the blood to clot. Von Willebrand factor is one of those proteins. It is made by the lining of cells in the wall of blood vessels (veins and arteries). When blood vessels are damaged, platelets (small blood cells that collect and stick together to plug cuts and breaks in blood vessels) clump together at the site of the injury. Von Willebrand factor acts like glue that helps the platelets stick together. Von Willebrand factor is also a carrier of clotting factor VIII, another protein that helps your blood to clot.
When there is not enough VWF in the blood, or when it does not work the way it should, the blood takes longer to clot.
Types of von Willebrand Disease:
Von Willebrand Disease is divided into three categories - Type 1, Type 2 and Type 3. Type 2 VWD is itself divided into several sub-types.
Partial quantitative deficiency of VWF. Typically autosomal dominant in inheritance although diagnosis is complicated by reduced penitrance and variable expressivity. Characterised by parallel reductions in VWF:Ag and Factor VIII. Multimer distribution is normal.
Qualitative VWF defect associated with absence of the largest multimers and low levels of VWF:Ricof activity relative to VWF:Ag. Generally autosomal dominant, caused by missense mutations within the VWF A2 repeat. Group 1 (defect in intracellular transport) or group 2 (increase in proteolysis in plasma after secretion).
Qualitative VWF defect associated with (usually) reduced high molecular weight multimers. Also enhanced ristocetin-induced platelet agglutination (RIPA) although VWF:Ricof may be normal. Inheritance is autosomal dominant.
Qualitative VWF defect associated with specific defects in platelet/VWF interaction but with a normal range of multimers. Inheritance is autosomal dominant.
Qualitative VWF defect resulting from defective VWF binding to FVIII and consequently low levels of circulating FVIII. Inheritance is autosomal recessive.
Clinically severe quantitative disorder resulting from a markedly reduced or absent platelet and plasma VWF (less than 5U/dL). FVIII activity also reduced. Usually autosomal recessive inheritance (or occasionally a manifestation of homozygous or compound heterozygous inheritance of type 1 VWD).
What cause it ?
The child of a man or a woman with vWD has a 50% chance of getting the gene for the condition. In types 1 and 2, a child has inherited the gene from one parent. In type 3, the child has inherited genes for the disease from both parents. Even if both parents have mild or no symptoms, the child can have severe symptoms. In rare cases, von Willebrand disease can be acquired (developed later in life).
Signs and Symptoms
The signs and symptoms depend on the type and severity of the disease. Some people have the gene for the disease but do not have bleeding symptoms.
Patients with Type 1 and Type 2 disease may have the following mild to moderate bleeding symptoms:
-- Bleeding from the gums after a dental procedure
-- Heavy menstrual bleeding in women
-- Blood in their stools (from bleeding in the intestines or stomach)
-- Blood in their urine (from bleeding in the kidneys or bladder)
-- Excessive bleeding after a cut or other accident
-- Excessive bleeding after surgery.
Heavy menstrual bleeding is the most common symptom in women. If untreated, it can lead to iron deficiency and anemia. Doctors usually test for the disease in women who have heavy menstrual bleeding. Some people may only be diagnosed after an episode of prolonged bleeding after an accident or surgery.
Patients with Type 3 disease (rare and severe) are usually diagnosed in childhood. They may have:
-- Severe bleeding episodes for no reason. These bleeding episodes can be life threatening without immediate treatment.
-- Bleeding into soft tissues or joints, causing severe pain and swelling. Bleeding into the joint is called hemarthrosis.
Because its symptoms can be mild, vWD can be difficult to diagnose. In addition to doing a physical examination, the doctor will ask you about any concerns and symptoms you have, your past health, your family's health, any medications you're taking, any allergies you may have, and other issues, such as bleeding problems in other familiy members.
Specific tests for the disease must be done because some people with a mild form of the disease (Type 1) may have normal results on the usual test for bleeding disorders. If you have bleeding symptoms, your doctor will order blood tests that specifically check:
-- The level of von Willebrand factor in your blood
-- How well the von Willebrand factor works
These tests should be repeated several times in order to be sure of the diagnosis.This is because a person's test results can be normal one day and abnormal a month later. There are a number of things that cause the level of VWF to rise in the blood. Some of them are:
* having an infection
* doing a lot of exercise
* being on the Pill (oral contraceptives).
For many teens with vWD, the condition doesn't require big lifestyle changes. Teens with more severe vWD should avoid unnecessary trauma, including contact sports like football and hockey, but other sports and activities are usually OK. If bleeding does occur, applying pressure to the area may be all that's needed. If the person gets a nosebleed, he or she should put pressure on the bridge of the nose to help stop the bleeding. Girls with vWD who have started their periods might want to carry extra pads or even a change of clothes in case of accidents. Sometimes, the doctor may prescribe birth control pills to help control heavy menstrual bleeding.
If these measures aren't enough to prevent or control bleeding problems, additional types of treatment may be needed. The most common treatment used for type 1 von Willebrand disease is a drug known as desmopressin. This medication causes a temporary increase in the von Willebrand factor level in the person's blood. It can be given by injection or intranasally (into the nose). Desmopressin may or may not be helpful for treating people with type 2 von Willebrand disease.
Patients with type 3 (and some with type 2) disease will need treatment with a medication that contains both factor VIII and von Willebrand factor. This medication is given intravenously (injected into a vein).
Patients with type 1 may also need this medication in certain situations, such as after major trauma or major surgery, although they can generally be treated with desmopressin.
Your doctor will order a combination of blood tests to diagnose the disease. These tests may include:
-- Ristocetin (ris-too-SEE-tin) cofactor activity. This test shows how well the von Willebrand factor works. Test for factor VIII clotting activity - Some people with von Willebrand disease will have low levels of factor VIII activity, while others will have normal levels.
-- Von Willebrand factor multimers - This test shows the makeup or structure of the von Willebrand factor. It helps your doctor diagnose what type of disease you have.
-- Platelet function test - This test measures how well your platelets are working.
Tests to find whether
* what type of VWD the person has. are,
Bleeding time - This measures the length of time it takes for a simple cut to stop bleeding.
Factor VIII:C - This measures the amount of Factor VIII clotting activity.
VWF: antigen - This measures the amount of Von Willebrand Factor.
Ristocetin cofactor activity - This measures how well the VWF works.
VWF multimers - This measures the structure of the VWF.
Platelet function tests - These measure how well the platelets work.
Most cases of von Willebrand disease are mild and often do not require treatment. Treatment may only be needed after a surgery, tooth extraction, or an accident. There is no cure for VWD, but it can be treated. For those who need treatment, one or more of the following may be used:
-- Medication to prevent breakdown of clots
-- Medication to control heavy menstrual bleeding in women
-- Injection of clotting factor concentrates (containing von Willebrand factor and factor VIII).
Your doctor will decide what treatment you need based on the severity and the type of disease your have. Specific treatments include:
Desmopressin (DDAVP)- is a synthetic hormone usually given by injection or nasal spray. It works by making the body produce more von Willebrand factor, which also increases the level of factor VIII activity. DDAVP is effective in treating most patients with Type 1 disease and some with Type 2a disease.
Replacement therapy - is the injection of a concentrate of von Willebrand factor and factor VIII. This treatment can be used in:
Patients who cannot take DDAVP or who need prolonged treatment
Patients with Type 1 disease who do not respond to DDAVP
Patients with Type 2b disease
Patients with Type 3 disease.
Oral contraceptives (or birth control pills) - can help women who have heavy menstrual bleeding. The hormones in the pills can increase von Willebrand factor and factor VIII activity.
Antifibrinolytic drugs - help prevent the breakdown of clotting factors in the blood. They are used mostly in von Willebrand patients to stop bleeding following minor surgery, tooth extraction, or an injury. They may be used alone or together with DDAVP and replacement therapy.
Fibrin glue - is medicine placed directly on a wound to stop the bleeding.
Thrombin - is a natural clotting agent that comes in powder form. Bleeds in the mouth or nose can be stopped by applying Thrombin directly to the bleeding site.
Cyklokapron and Amicar - Cyklokapron (tranexamic acid) and Amicar (aminocaproic acid) are drugs that help to hold a clot in place once it has formed. They act by stopping the activity of an enzyme, called plasmin, which dissolves blood clots.
They do not help to actually form a clot. This means they can not be used instead of desmopressin or VWF concentrate.
Cryoprecipitate - Cryoprecipitate is a blood component made from plasma. It was commonly used to treat VWD in the past. However, because there is no method to kill viruses in cryoprecipitate, it is no longer recommended.
Living with von Willebrand Disease :
It is important that you try to prevent bleeding and stay healthy. You should:
-- Other nonsteriodal anti-inflammatory drugs
-- Always check with your doctor before taking any medication.
-- Tell your doctor or dentist that you have von Willebrand disease. You can receive medication before dental work that reduces bleeding.
-- Wear a medical ID bracelet so that in case of serious injury or accident, the doctors caring for you will know about your disease.
-- Exercise regularly and maintain a healthy weight. Exercise helps keep muscles flexible and helps prevent damage to muscles and joints. Always stretch before exercising. Some safe exercises or activities are swimming, biking, and walking. Football, hockey, wrestling, and weightlifting (heavy weights) are not safe activities if you have had bleeding problems. Always check with your doctor before starting any exercise program.
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