Platform
Company
Immunology & Autoimmune
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Currently under review
Pending specialist review and validation.
This test measures the amount of von Willebrand factor, a blood protein that helps platelets stick to sites of injury and supports normal clotting. The result reflects how much of the protein is present, not how well it works.
The term preliminary indicates this is an initial antigen measurement that is often paired with other tests of von Willebrand factor function and structure. Your clinician may use it as a screening step in a broader evaluation of bleeding symptoms.
Your clinician may order this test if you have easy bruising, frequent nosebleeds, heavy menstrual bleeding, prolonged bleeding after dental work or surgery, or a family history of a bleeding disorder. It helps assess for von Willebrand disease and related conditions that affect clotting.
Von Willebrand factor levels can change with stress, infections, inflammation, pregnancy, and certain therapies. Knowing the amount of this protein helps determine whether additional specialized tests are needed and guides decisions about treatment or planning for procedures.
A result within the expected reference interval suggests a typical amount of von Willebrand factor, but it does not exclude a functional problem. Some people have normal amounts of the protein yet still have impaired function, which requires different tests to detect.
A lower-than-expected result can suggest inherited or acquired von Willebrand factor deficiency. A higher result can be seen with inflammation, stress, pregnancy, or as part of the body’s response to illness. If results are unexpected, your clinician may repeat testing when you are well, consider your blood group, and add functional assays or related studies. Do not change medications on your own; discuss next steps with your care team.
Reference intervals vary by laboratory, analyzer, methodology, population, and units. The ranges shown here are for education only. Always interpret your results against the reference interval printed on your own lab report.
Acute infections, inflammation, physical stress, and vigorous exercise can temporarily raise von Willebrand factor levels, which may mask a deficiency if testing is done during these periods.
Inherited differences, including your ABO blood group and gene variants, influence baseline von Willebrand factor amounts, so some people naturally run lower or higher than others.
Pregnancy and estrogen-containing therapies can elevate von Willebrand factor, potentially altering test interpretation during prenatal care or while on hormonal treatment.
Desmopressin, vasopressin analogs, and von Willebrand factor concentrates can increase levels, while some conditions or drugs associated with heart disease or autoimmune issues may reduce them.
Improper collection, prolonged tourniquet time, or delayed processing can affect results. When possible, testing should be done when you are clinically stable and not acutely ill.
Levels tend to rise with age and with inflammatory conditions, which can lead to higher results that do not necessarily reflect a bleeding risk.
References