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von Willebrand Factor Antigen (VWF:Ag)

Published: August 9, 2026Updated: August 16, 2026

This test measures the amount of von Willebrand Factor (VWF) protein in your blood, which helps blood clot. Low levels may indicate bleeding disorders or other conditions.

Quick summary

["VWF levels help diagnose bleeding risks or related blood disorders."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 16, 2026Editorial policy

Key facts at a glance

LOINC
48595-3
Short code
von Willebrand eval PPP-Imp
Synonyms
von Willebrand eval PPP-Imp
Category
chemistry
Sample
plasma
Container
Lavender-top (EDTA) or Green-top (Heparin)
Units
N/A
Ref low
44
Ref high
147
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
CPT
84075
SNOMED
27550007
Specimen volume
5 mL
Stability
Room temperature: 4h, Refrigerated: 24h, Frozen: 7d
Hemolysis max
500
Lipemia max
1000
Icterus max
500
TAT
4–24 hours
Order
routine

Why This Test Is Done

Your doctor may order this test if you have symptoms like excessive bleeding (e.g., nosebleeds, heavy menstrual periods, easy bruising), prolonged bleeding after surgery, or if you have a family history of bleeding disorders. It may also be used to monitor treatment for von Willebrand disease or other clotting conditions.

How the Test Works

A blood sample is taken from a vein in your arm. The sample is sent to a lab where it is analyzed using an immunoassay method to detect and quantify VWF protein levels.

Sample Collection

You’ll typically have a small needle inserted into your arm to draw blood. This process is quick and usually causes only minor discomfort. You may feel a slight pinch or sting, but most people tolerate it well. Rest for a few minutes afterward to avoid excessive bruising.

What to Expect Before the Test

No special preparation is needed for this test. However, inform your doctor about any medications you’re taking, especially blood thinners like warfarin or aspirin, as they may affect your results.

Reference range

Adult: 44-147 U/LN/A

Specimen: plasma

No special preparation required. Avoid fatty meals before the test if possible.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

VWF Antigen

Frequently asked questions

What Does a Low or High VWF Level Mean?
A low VWF level may suggest bleeding problems or von Willebrand disease. A high level could indicate inflammation, pregnancy, or other conditions. Your doctor will discuss results with you based on your health needs.
How Often Should I Get This Test?
Your doctor will determine the frequency based on your symptoms, medical history, and treatment plan. Regular monitoring may be needed if you have a bleeding disorder or are on treatment for it.
Can Diet or Supplements Affect VWF Levels?
While certain medications (like blood thinners) can influence VWF levels, diet or supplements typically do not directly affect this test. Always check with your doctor before starting new supplements.
  1. 1
    MedlinePlus — Laboratory TestsSource
  2. 2
    Lab Tests OnlineSource
  3. 3
    Mayo Clinic — Tests & ProceduresSource

Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.

This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.

Medical Disclaimer

This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.

If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.

Medically reviewed by WellAlly Editorial Team Last reviewed August 16, 2026. · Read our editorial policy