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HIV Antibody and P24 Antigen Screening Test (Serum/Plasma)

Published: August 9, 2026Updated: August 17, 2026

This test checks for antibodies and the p24 protein, which are markers of HIV infection, in your blood. It helps determine if you’ve been exposed to the virus.

Quick summary

["Early detection of HIV infection is critical for managing your health and preventing complications."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 17, 2026Editorial policy

Key facts at a glance

LOINC
43185-8
Short code
HIV 1 & 2 Ab Patrn Ser IB-Imp
Synonyms
HIV 1 & 2 Ab Patrn Ser IB-Imp
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Ref low
0
Ref high
17
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
ib
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 for You

HIV can spread silently for years without symptoms, so testing is essential—especially if you’ve had risk exposures like unprotected sex, shared needles, or other behaviors that increase risk. This test screens for both antibodies (which develop after infection) and the p24 protein (a marker of active virus). Early diagnosis allows for timely treatment to improve outcomes.

How the Test Works

Your blood sample is tested using a combination of immunoassay methods to detect HIV antibodies and the p24 antigen. The test looks for evidence of past or current infection, not the virus itself.

What to Expect Before the Test

No special preparation is needed. You may have a small needle inserted to draw blood from your arm. If you’re nervous, let your provider know—they can offer options like numbing cream or distraction techniques.

What to Expect After the Test

You’ll likely feel minor bruising or discomfort at the injection site, which may last a few hours. Avoid vigorous activity for 24 hours to prevent excessive bleeding. If you notice unusual bleeding or signs of infection (like swelling/pain), contact your provider.

Reference range

NCBI: NSE 0-17 ng/mLN/A

Specimen: serum

No special preparation required. Some tests may require follow-up confirmatory testing.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

HIV Test (Screen)

Frequently asked questions

How soon after exposure should I get tested?
If you’ve had recent exposure (like unprotected sex or needle sharing), testing is recommended within 4–6 weeks after exposure, even if you don’t have symptoms. Early testing improves treatment options.
What if I get a positive result?
A positive result triggers a follow-up test (like a confirmatory HIV antibody test) to confirm the diagnosis. Your healthcare provider will guide you through next steps, including treatment options and support services.
Can I still be tested if I’m pregnant?
Yes, HIV testing is highly recommended during pregnancy. It’s the best way to prevent mother-to-child transmission and ensures you receive the care you need for both yourself and your baby.
  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 17, 2026. · Read our editorial policy