Factor VIII Inhibitor (Plasma) – 4-Hydroxybenzoic Acid Immunoassay
This test measures the presence of antibodies that can interfere with blood clotting by blocking Factor VIII, a protein essential for normal clotting. It’s used primarily in patients suspected of having an acquired Factor VIII inhibitor, which can complicate treatment for hemophilia.
["This test helps diagnose rare blood clotting disorders caused by immune system attacks on Factor VIII."]
Key facts at a glance
- LOINC
- 95122-8
- Short code
- Fact VIII Inhib PPP Chro-Imp
- Synonyms
- Fact VIII Inhib PPP Chro-Imp
- 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
- chromo
- 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 recommend this test if you have hemophilia (a genetic bleeding disorder) and experience unusual bleeding or clotting issues despite receiving Factor VIII replacement therapy. It’s also used to monitor patients with suspected Factor VIII inhibitor development during treatment.
What to Expect Before the Test
No special preparation is needed. A blood sample will be drawn from a vein, usually in your arm. You may feel slight discomfort, but it’s typically over quickly. If you’re on blood thinners, inform your provider beforehand.
What the Test Results Mean
Results are qualitative (present or absent) and indicate whether antibodies blocking Factor VIII are detected. High levels suggest an inhibitor is present, which may require alternative treatment approaches.
Common Causes and Risks
Acquired Factor VIII inhibitors most commonly develop in patients with hemophilia who receive Factor VIII replacement therapy, though rare cases occur in others with bleeding disorders or autoimmune conditions.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Clinical Significance: Factor VIII inhibitors disrupt normal clotting by neutralizing Factor VIII, leading to prolonged bleeding risks. Diagnosis is critical for adjusting treatment plans to prevent severe bleeding episodes, especially in surgical or trauma settings.
Short name
Factor VIII Inhibitor (4-HBA IA)
Frequently asked questions
What triggers this test?
How long does it take to get results?
Can lifestyle changes affect this test?
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