: Factor VIII Antigen [Mass or Activity] in Platelet-Poor Plasma by Immunoassay
: This test measures the amount or activity of factor VIII, a blood clotting protein, in a sample of platelet-poor plasma. It helps evaluate bleeding or clotting disorders related to factor VIII.
[": Factor VIII testing helps determine whether a person has too little or abnormal factor VIII, which affects blood clotting."]
Key facts at a glance
- LOINC
- 3214-4
- Short code
- Fact VIII Ag PPP IEP-aCnc
- Synonyms
- Fact VIII Ag PPP IEP-aCnc
- Category
- chemistry
- Sample
- plasma
- Container
- Lavender-top (EDTA) or Green-top (Heparin)
- Units
- N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Method
- immunoelectrophoresis
- 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
: What Is Being Tested?
: Factor VIII is one of the proteins in your blood that helps form clots to stop bleeding. This test measures factor VIII antigen (the amount of the protein present) or its activity in platelet-poor plasma using an immunoassay method.
: Why the Test Is Ordered
: Your healthcare provider may order this test if you have unusual bleeding or bruising, a family history of bleeding disorders, or to monitor a known condition such as hemophilia A or von Willebrand disease. It may also be part of an evaluation for abnormal clotting.
: How the Sample Is Collected
: A blood sample is drawn from a vein, usually in your arm, and processed to separate plasma from blood cells. The plasma is then analyzed in the laboratory. No special preparation is typically required unless your provider instructs otherwise.
: What the Results Mean
: Results are compared with a reference range established by the laboratory. Lower-than-expected factor VIII levels may suggest a deficiency or bleeding disorder, while higher levels can occur with inflammation, stress, or other conditions. Your provider will interpret results alongside your symptoms and other tests.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
: Factor VIII testing is important for diagnosing and managing bleeding disorders such as hemophilia A and von Willebrand disease, and for assessing clotting risk. Results should always be interpreted by a healthcare professional in the context of your medical history.
Short name
: Factor VIII Antigen
Frequently asked questions
: Do I need to fast before this test?
: Can medications affect the results?
: Is this test painful?
Sources
- 1
- 2Lab Tests OnlineSource
- 3
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.
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