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HIV-1 Antibody and p24 Antigen Screening and Confirmatory Test (Serum/Plasma)

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

This test detects antibodies and the p24 protein from HIV-1, helping identify if you have been exposed to the virus. It’s used as part of routine screening and confirmation for HIV infection.

Quick summary

This test helps determine if HIV-1 antibodies or viral protein are present in your blood, guiding next steps in care.

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

Key facts at a glance

LOINC
58900-2
Short code
HIV 1+2 Ab+HIV1 p24 Ag SerPl IA-aCnc
Synonyms
HIV 1+2 Ab+HIV1 p24 Ag SerPl IA-aCnc
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
ia
CPT
86701
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 Matters

HIV-1 screening is critical for early detection. Antibodies (IgG/IgM) develop after initial infection, while the p24 antigen may appear earlier but is less sensitive. This test combines both methods to improve accuracy in identifying active infection.

How the Test Works

The test uses immunoassay (IA) methods to detect HIV-1 antibodies (IgG/IgM) and p24 antigen in serum or plasma. Antibody testing identifies past or current infection, while p24 antigen testing may indicate recent exposure.

Sample Collection and Preparation

A blood sample is drawn from a vein, typically in the arm. The blood is processed to separate serum or plasma for testing. This sample is sent to a lab for analysis.

Test Results Interpretation

Results are reported as positive, negative, or indeterminate. A positive result requires further confirmation testing. Negative results mean no detectable antibodies or p24 antigen at the time of testing.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance

Short name

HIV-1 Screening & Confirmation

Frequently asked questions

What does a positive result mean?
A positive result indicates potential HIV-1 infection. Follow-up testing (e.g., Western blot or nucleic acid testing) is recommended to confirm diagnosis. Early detection allows for timely treatment and support.
Why might I need this test?
You may need this test if you have risk factors for HIV (e.g., unprotected sex, shared needles), are part of a high-risk group, or are part of a routine screening program. It’s also used to confirm initial positive screening results.
What if my test is negative but I suspect I was exposed?
A negative result means no detectable antibodies or p24 antigen at the time of testing. If you suspect exposure, wait 3 months before retesting, as antibodies may take time to develop. Consult your healthcare provider for guidance.
  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