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Fluorescent Antibody Titration for Viral Antigen (Serum/Plasma)

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

This test measures the presence and level of a specific viral antigen in your blood using a fluorescent antibody technique. It helps determine if you have an active infection by the virus.

Quick summary

["Assesses active viral infection through antigen detection in blood samples."]

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

Key facts at a glance

LOINC
22823-9
Short code
FLUAV Ab Titr Ser Aggl
Synonyms
FLUAV Ab Titr Ser Aggl
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
aggl
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

How the Test Works

Your blood sample is tested using a fluorescent antibody method. Antibodies tagged with a fluorescent dye bind to the virus’s antigens. If the virus is present, the fluorescence signal increases, indicating an active infection.

What to Expect Before the Test

No special preparation is needed. You may have a small needle inserted to draw blood from a vein in your arm. The process usually takes a few minutes, and you can resume normal activities afterward.

Common Uses for This Test

This test is often used to diagnose acute viral infections, such as certain respiratory or systemic viral illnesses, where antigen detection can confirm active infection before antibody levels rise.

What Results Mean

A positive result indicates the presence of the viral antigen, suggesting an active infection. A negative result means the antigen was not detected, which may mean no active infection is present or the test was taken too early.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance

Short name

Viral Antigen Fluorescent Antibody Test

Frequently asked questions

Why might my doctor order this test?
Your doctor may recommend this test if you have symptoms of an infection (e.g., fever, fatigue, respiratory issues) and suspect a viral cause. It can help confirm an active infection quickly, especially when antibodies have not yet developed.
What if my results are positive?
A positive result means you likely have an active viral infection. Your doctor may recommend further testing, treatment, or monitoring to address the infection and manage symptoms.
How soon can I expect results?
Results are typically available within 1 to 3 business days, depending on lab processing times. Follow-up with your healthcare provider for interpretation and next steps.
  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