What Is von Willebrand Factor?
Von Willebrand factor (VWF) is a protein crucial to the blood clotting process. If you don’t have enough of this protein, or if it doesn’t work as it’s supposed to, you may have von Willebrand disease (VWD), a bleeding disorder.
VWD is the most common inherited bleeding disorder. Bleeding disorders disrupt your body’s typical healthy blood clotting process.
Experts estimate that VWD affects up to 1% of the population, though the number of people with serious bleeding symptoms is much lower. Affected people might notice symptoms ranging from nosebleeds and heavy periods to internal bleeding.
All cases of VWD are ultimately due to weak or improper activity of VWF, a large protein that plays a crucial role in hemostasis, the process of blood clotting.
Most cases of VWD are due to changes in the genes that make VWF. Very rarely, the disease can develop later in life, resulting from other medical conditions affecting your VWF levels and activity.
What does von Willebrand factor do?
The VWF gene is located on chromosome 12. It encodes for VWF, a complex protein with several different active sites called domains. Each of these domains plays a different role in your blood clotting process.
VWF regularly circulates in your bloodstream at baseline levels. When you’re bleeding, your body releases more VWF from your platelets and the cells lining your blood vessels.
At the site of injury, each domain of VWF performs different key functions, including:
What does high or low von Willebrand factor mean?
VWF typically circulates in your bloodstream in a wide range of normal values. These can range from 50 to 200 international units per deciliter (IU/dL).
This is because your VWF level can vary according to your age, blood type, and other factors. Scientists have so far identified 19 different genetic loci involved in regulating plasma VWF levels. Circulating VWF is cleared rapidly from your bloodstream, with a half-life of about 16 hours, but this clearance rate is also highly variable.
A doctor might suspect VWD if you have very low VWF levels (under 30 IU/dL). They might also consider VWD at levels of 30 to 49 IU/dL if you have significant bleeding problems. Mildly low VWF levels are common in the larger population, but many people with low VWF don’t have noticeable bleeding issues.
High VWF levels may be due to genetic changes or environmental factors like inflammation. Persistently high VWF levels may be linked to a higher blood clotting risk.
How do doctors test von Willebrand factor levels?
When considering a bleeding disorder, a doctor will often start by performing a complete blood count and other coagulation tests. If they suspect VWD, they might order the following tests:
Additional testing is available to distinguish the type of VWD you might have. This can include VWF multimer and propeptide levels and desmopressin challenge testing. Genetic testing might help differentiate among the type 2 VWD subtypes.
What can affect von Willebrand factor levels?
VWF is a large protein with many different functions. Scientists have identified several mutations in the VWF gene, all with different outcomes.
Your VWF levels may be low if you have genetic changes causing reduced or absent production of VWF (as seen in VWD disease types 1 and 3) or unusually rapid inactivation and clearance of VWF or VWF multimers from your bloodstream (seen in type 1 and acquired VWD).
However, you can still have VWD when your VWF levels appear typical. Some people have gene mutations that cause their body to produce ineffective or dysfunctional VWF. In this case, the VWF level appears normal, but VWF activity and effectiveness are low. This is characteristic of type 2 VWD.
Takeaway
VWD is the most common genetic bleeding disorder. It usually causes symptoms like excessive nose, gum, or menstrual bleeding.
All types of VWD result from inadequate activity of VWF, a large and complex protein. Although it’s not one of your numbered clotting factors, VWF is critical to the blood clotting process.
If VWD runs in your family, or you’ve received a diagnosis of VWD, you might have reduced or absent production of VWF. Gene changes might also cause your body to make an altered VWF protein that can’t perform its usual functions to help your blood clot. You might also have unusually rapid clearance of VWF from your bloodstream.
A doctor can help you understand your VWF levels and activity, as well as how this could affect your treatment plan.
Thank you for this insightful post on von Willebrand Factor! It’s fascinating to learn about its role in blood clotting and its importance in managing bleeding disorders like von Willebrand disease. Your explanation on how it helps platelets stick together and adhere to blood vessel walls really clarifies its critical function. This information is incredibly valuable for anyone trying to understand the complexities of the human body’s clotting mechanism. Great job!
This is a fantastic explanation of von Willebrand Factor! It’s fascinating to learn about its crucial role in blood clotting, helping platelets stick together and adhere to blood vessel walls. Understanding vWF’s importance significantly advances our knowledge of bleeding disorders like von Willebrand Disease. Thanks for sharing this detailed and insightful post!
This article provides a very clear and informative overview of von Willebrand Factor (vWF). It’s great to learn about how this essential protein plays a critical role in blood clotting and how its deficiency or dysfunction can lead to bleeding disorders like von Willebrand disease. Understanding these mechanisms can really help demystify some of the complexities behind blood clotting for those of us not in the medical field. Thank you for sharing!
Thanks for the detailed post on von Willebrand Factor! It’s fascinating to learn about its crucial role in blood clotting and how deficiencies can lead to disorders like von Willebrand disease. Your explanation helps demystify a complex topic and underscores the importance of early diagnosis and treatment. Great job!
Thanks for the thorough explanation! I never realized how important von Willebrand Factor is in blood clotting and how its deficiency can lead to disorders like von Willebrand disease. This really highlights the complexity of our circulatory system. Great read!