von Willebrand Disease
All parents deal with their child's bruises and bloody noses from time to time. For most kids, a bandage and a sympathetic hug are all it takes to get them back in the game.
But a small number of kids have frequent nosebleeds, unexplained bruising, or prolonged bleeding after a tooth is pulled. Such excessive or prolonged bleeding could be a sign of a genetic disorder known as von Willebrand disease.
For many kids with this disorder, the symptoms are so mild that they never know they have it. Those with a more severe form of the disease, though, need proper diagnosis and a treatment plan to help them lead normal, active lives.
About von Willebrand Disease
Von Willebrand disease, or vWD, is an inherited disorder 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 (including hemophilia) are rare. Von Willebrand disease is the most common inherited bleeding disorder, affecting about 1% of the population.
Normally, bleeding occurs when a blood vessel is cut or torn. The blood's ability to clot (to plug the hole in the blood vessel and stop the flow of blood) is a complex process involving platelets and proteins called clotting factors. Von Willebrand factor is involved in the early stages of blood clotting, and also carries the important clotting protein factor VIII. (Factor VIII is the protein that is missing or defective when someone has hemophilia.)
People with vWD have bleeding problems because the levels or functioning of these blood components needed for clotting are abnormal.
Types of von Willebrand Disease
As with many conditions, there are various forms of vWD. Unlike hemophilia, which affects only boys, vWD affects boys and girls equally.
- In Type 1, the level of von Willebrand factor in the blood is reduced; the level of factor VIII also might be reduced. This is the most common and mildest form of the disease — the symptoms might be so minor that the person isn't ever diagnosed. People with Type I vWD usually do not bleed spontaneously but can have significant bleeding with trauma, surgery, or when they have a tooth pulled.
- In Type 2, the level of von Willebrand factor in the blood is
normal, but doesn’t work properly. Within this type are several subtypes:
- Type 2A: the building blocks that make up the factor (called multimers) are smaller than usual or break down too easily
- Type 2B: the factor sticks to the platelets too well, leading
to clumping of the platelets, which can cause a low platelet number
Other type 2 subtypes exist, but are much rarer.
- Type 3 patients have very low or absent von Willebrand factor and factor VIII. Symptoms are severe and may include bleeding into joints and muscles.
- Pseudo, or platelet-type, von Willebrand disease is similar to Type 2B, but the defect is in the platelets instead of in the factor.
Causes of vWD
Like hemophilia, vWD is a genetic disorder that is usually passed from parent to child (very rarely, it can be acquired after birth). The child of a man or a woman with vWD has a 50% chance of getting the gene.
In types 1 and 2, a child can inherit the gene for the disease from one parent only. In type 3, the child usually needs to inherit the gene from both parents. In those cases, the child will likely have severe symptoms, even if the parents don't have any symptoms at all. Also, a child can inherit the gene and show no symptoms, but as a carrier can pass the gene on to any offspring.
Signs and Symptoms
The symptoms of von Willebrand disease can include:
- bruising that's unusual in location or frequency
- abnormal menstrual bleeding
- bleeding in the mucous membranes, such as the gums, nose, and lining of the gastrointestinal system
- excessive or prolonged bleeding after a tooth is pulled or tonsils are removed or prolonged oozing from cuts
- excessive or prolonged bleeding after circumcision
Diagnosis and Treatment
Because symptoms can be mild, vWD can be difficult to diagnose and often goes undetected.
Blood tests used to diagnose vWD include:
- von Willebrand factor antigen test, which measures the amount of von Willebrand factor
- von Willebrand activity test (also called ristocetin cofactor or RCF activity test), which measures how well the von Willebrand factor works
- factor VIII activity test (also called factor VIII coagulant assay), which measures the level of factor VIII and its ability to function
- von Willebrand multimers test, which helps to classify the type of von Willebrand disease
- platelet function tests, which determine how well the platelets work
Tests might need to be repeated because the levels they detect may rise and fall over time. Also, the doctor will take a family medical history to see if other relatives have a bleeding disorder.
The most common treatment for vWD is desmopressin, a medication that causes a temporary increase in the von Willebrand factor and factor VIII levels. It can be given intravenously (into a vein) or intranasally (into the nose), but may be ineffective in treating Type 2A or Type 2B.
People with Type 3 (and some with Type 2A and 2B) will need treatment with Humate-P, an intravenous medication derived from human plasma that contains factor VIII and von Willebrand factor. Those with Type 1 also might receive Humate-P in certain situations, such as major trauma or major surgery, although they usually can be treated with desmopressin.
Medication to inhibit the breakdown of blood clots (such as aminocaproic acid) also might be used.
Kids with vWD should avoid unnecessary trauma, including contact sports. If bleeding does occur, apply pressure to the area. During nosebleeds, pinch the soft part of the nose and have the child lean slightly forward to keep the blood from flowing down the throat.
Because of the possibility of excessive bleeding, male infants who are at risk for vWD (those with a family history of the disease) should not be circumcised without a doctor's OK.
Girls with vWD who have started their periods might want to take extra pads or a change of clothes in case of accidents. Heavy menstrual bleeding sometimes can be controlled with birth control pills.
Kids with vWD should not take aspirin and other non-steroidal anti-inflammatory drugs (such as ibuprofen) for pain or fever. These drugs interfere with platelet function and can increase the risk of bleeding. It is safe to take acetaminophen, which doesn't affect platelet function.
Call your doctor immediately if your child experiences any excessive or unexplained bleeding.