When a child has frequent nosebleeds, easy bruising, or unusual bleeding after injuries or surgery, doctors may recommend a blood test that measures a protein called von Willebrand factor (VWF). This test helps check for von Willebrand disease (VWD), the most common inherited bleeding disorder in children and adults.
This guide explains, in parent-friendly language, why the VWF test is done, what happens before and during the test, what the different parts of the test mean, and how results can guide treatment if your child has a bleeding problem.
1. What Is von Willebrand Factor?
Von Willebrand factor is a blood-clotting protein that helps stop bleeding in two major ways:
- It acts like a glue, helping platelets (tiny blood cells) stick to the wall of a damaged blood vessel.
- It carries and protects another clotting protein called factor VIII, helping the body build a more stable clot.
If there is too little VWF or if the protein does not work properly, blood may not clot as it should. This can cause symptoms such as:
- Frequent or long-lasting nosebleeds
- Easy or unexplained bruising
- Prolonged bleeding from cuts
- Heavy bleeding after dental work or surgery
- In menstruating adolescents, heavy periods (using many pads or tampons per day or bleeding longer than a week)
Because symptoms can be mild, some children with von Willebrand disease may not be diagnosed until they have surgery, lose a tooth, or begin menstruating.
2. Why Might My Child Need a VWF Test?
Pediatricians or pediatric hematologists (blood specialists for children) may order von Willebrand factor testing if they see signs that your child’s blood does not clot normally.
Common reasons for testing
- Frequent nosebleeds that are hard to stop
- Easy bruising, especially large or raised bruises from minor bumps
- Bleeding that lasts longer than expected after cuts, dental extraction, or minor surgery
- Family history of
- von Willebrand disease
- other bleeding disorders (like hemophilia)
- heavy bleeding with childbirth, tooth pulling, or operations
- Very heavy menstrual periods in teens, especially if present from the first period
- Abnormal results on other screening blood tests for clotting
Sometimes VWF testing is done before planned surgery if your child’s history raises any concern about bleeding risk, or if a close relative is known to have a clotting disorder.
3. Types of von Willebrand Disease (and How Testing Helps)
The von Willebrand factor test is usually part of a panel of blood tests that helps doctors determine whether a child has von Willebrand disease and, if so, which type.
| Type of VWD | What is happening? | Typical severity |
|---|---|---|
| Type 1 | VWF level is lower than normal, but the protein usually works fairly well. | Mild; most common form. |
| Type 2 | VWF amount may be normal or slightly low, but it does not function properly. | Usually mild to moderate; several subtypes. |
| Type 3 | Very little or almost no VWF in the blood; factor VIII is also low. | Severe; rare but can cause serious bleeding. |
Different test combinations and patterns point to different types of VWD, which is important because treatment and planning for dental work, sports, and surgery may change depending on the type and severity.
4. What Does the VWF Test Measure?
When doctors talk about a “VWF test,” they are usually referring to a group of blood tests that examine both the amount and the function of von Willebrand factor.
Core tests often included
- VWF antigen
- Measures how much von Willebrand factor is present in the blood.
- Helps identify low levels, as in type 1 and some type 2 VWD.
- VWF activity (function) test
- Assesses how well VWF works to help platelets stick and clot.
- Can be low even when the antigen level is near normal in some type 2 variants.
- Factor VIII activity
- Measures the level of clotting factor VIII, which is carried by VWF.
- Often reduced in more severe VWD, especially type 3.
Depending on the initial results, additional specialized tests may be done to look at the size distribution of VWF multimers, platelet function, or genetic changes. These are usually arranged by a pediatric hematologist.
5. Preparing Your Child for the Test
VWF testing uses a blood sample taken from a vein. Preparation is usually simple, but certain factors can change VWF levels and make test interpretation more difficult.
Factors that can affect VWF results
- Recent illness or infection: VWF levels can rise during infections or inflammation and may temporarily look closer to normal.
- Stress and exercise: Both can increase VWF levels for a short time.
- Hormones: Pregnancy, hormonal birth control, or certain hormone treatments can influence VWF.
- Iron deficiency anemia and other medical conditions may also affect clotting tests.
Because of these issues, doctors sometimes repeat the test at a different time, especially if the first result is borderline or does not match your child’s symptoms.
What parents can do in advance
- Ask whether your child should fast (most VWF tests do not require fasting, but follow your lab’s instructions).
- Provide a complete list of your child’s medications and supplements, including over-the-counter pain relievers or herbal remedies.
- Tell the care team if your child has recently been ill, had a vaccine, or has had significant stress, such as a recent injury.
- Prepare your child by explaining in simple terms that a small amount of blood will be taken with a needle and that it will be quick.
6. What Happens During the Blood Test?
VWF testing is done in a clinic, hospital lab, or outpatient laboratory. The process is similar to any other blood draw:
- Your child will sit or lie down. A tourniquet is placed on the arm to make the vein more visible.
- The skin is cleaned with an antiseptic wipe to prevent infection.
- A small needle is inserted into a vein, usually in the arm or hand, and blood is collected into one or more tubes.
- The needle is removed, and pressure is applied to stop any bleeding. A small bandage is placed.
The blood sample is then sent to a specialized laboratory for analysis. Results are often available within several days, but complex testing can take longer.
Helping your child cope
- Bring a favorite toy, book, or device for distraction.
- Use deep-breathing or counting games to help them stay calm.
- For very anxious children, ask whether a numbing cream can be applied before the needle stick.
7. Understanding the Results
Only your child’s healthcare team can fully interpret the test results because they must consider age, medical history, other blood tests, and family patterns. In general, results may fall into one of three broad categories:
- Normal
- VWF amount and activity are within the lab’s reference range, and factor VIII is normal.
- This makes significant von Willebrand disease less likely, but other bleeding conditions may still be considered.
- Borderline or slightly low
- VWF levels are near the lower limit of normal.
- Doctors may repeat tests, review family history, and sometimes diagnose a mild VWD or classify results as “low VWF.”
- Clearly low or abnormal
- VWF antigen and/or activity are clearly below normal, and factor VIII may also be low.
- Patterns across the tests help identify type 1, 2, or 3 VWD.
Your child’s hematologist will explain what the numbers mean, discuss whether additional testing is needed, and work with you on a plan to reduce bleeding risks.
8. How Are von Willebrand Disease and Other Bleeding Problems Treated?
If testing confirms von Willebrand disease, treatment is tailored to the type of VWD, how often your child bleeds, and the situations that trigger bleeding.
Common treatment and prevention options
- Desmopressin (DDAVP)
- A synthetic hormone that helps the body release stored VWF and factor VIII into the bloodstream.
- Often used in children with mild type 1 and some type 2 VWD before surgery or to treat minor bleeding.
- Given as an injection or nasal spray depending on age and local guidelines.
- VWF-containing factor concentrates
- Infusions of purified VWF (often with factor VIII) for children who do not respond to desmopressin or have more severe disease, such as type 3.
- Antifibrinolytic medicines
- Drugs such as tranexamic acid help clots last longer in areas like the mouth, nose, or during menstrual bleeding.
- Hormonal treatments
- Hormonal birth control methods may help reduce heavy menstrual bleeding in teens with VWD.
Many children with mild VWD may only require treatment before dental work, surgery, or after certain injuries. Regular follow-up with a hematology clinic helps ensure your child has an up-to-date plan for school, sports, and emergency care.
9. Living With a Bleeding Disorder: Practical Tips for Families
A diagnosis of von Willebrand disease can be worrying, but with the right precautions and care, most children lead very active lives.
Safety and everyday life
- Inform all healthcare providers, dentists, and school nurses about your child’s diagnosis.
- Ask the hematology team whether your child should avoid certain medications, such as aspirin or non-steroidal anti-inflammatory drugs (NSAIDs), which can affect platelets.
- Discuss which sports and activities are safe; many children can fully participate with some adjustments.
- Have an emergency plan for serious injuries, including which hospital to go to and whether your child should carry a medical alert card or bracelet.
10. Frequently Asked Questions (FAQs)
Q1: Is the von Willebrand factor test painful?
The test uses a standard blood draw from a vein, so your child will feel a brief needle stick and some pressure. The discomfort usually lasts only a few seconds. Using distraction, deep breathing, or numbing cream can make the experience easier.
Q2: Can my child have von Willebrand disease even if no one else in the family does?
Yes. While VWD is often inherited, new (spontaneous) genetic changes can occur, or milder symptoms in older relatives may have gone unrecognized. Sometimes a child’s diagnosis is the first clue that other family members also have a bleeding tendency.
Q3: Will my child outgrow von Willebrand disease?
Von Willebrand disease is usually a lifelong condition because it is linked to the way the body makes von Willebrand factor. However, symptoms can change over time. Some children with mild VWD bleed very little as they get older, while others may notice more issues around surgeries or with heavy periods. Regular follow-up helps adjust the care plan as needs change.
Q4: How accurate is the VWF test?
The test is very useful but can be challenging to interpret because VWF levels rise and fall with illness, stress, and hormones. For this reason, doctors often repeat tests and review them in the context of bleeding symptoms and family history rather than relying on a single result.
Q5: What should I do if my child with VWD has a serious injury?
Apply firm pressure to any bleeding area and seek urgent medical care, preferably at an emergency department familiar with bleeding disorders. Let the team know your child’s diagnosis and which treatments have been recommended. Your child’s hematology clinic may provide an emergency letter to share with local hospitals.
References
- The diagnosis and treatment of von Willebrand disease in children — Blanchette VS, Rand ML. Paediatrics & Child Health. 2010-01-01. https://pmc.ncbi.nlm.nih.gov/articles/PMC2794822/
- Bleeding Disorders in Children: von Willebrand Disease and Hemophilia — American Academy of Pediatrics / HealthyChildren.org. 2022-04-01. https://www.healthychildren.org/English/health-issues/conditions/chronic/Pages/bleeding-disorders-in-children-von-willebrand-disease-and-hemophilia.aspx
- Von Willebrand Disease — UCSF Benioff Children’s Hospitals. 2023-01-01. https://www.ucsfbenioffchildrens.org/conditions/von-willebrand-disease
- Von Willebrand Disease — Seattle Children’s Hospital. 2021-06-01. https://www.seattlechildrens.org/conditions/von-willebrand-disease/
- Von Willebrand Disease — Boston Children’s Hospital. 2022-09-01. https://www.childrenshospital.org/conditions/von-willebrand-disease
- Von Willebrand Disease — Nationwide Children’s Hospital. 2020-11-01. https://www.nationwidechildrens.org/conditions/von-willebrand-disease
- Von Willebrand Disease: What It Is, Types, Symptoms & Treatment — Cleveland Clinic. 2023-05-10. https://my.clevelandclinic.org/health/diseases/17709-von-willebrand-disease
