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HIV p24 Antigen Quantitative, Serum/Plasma

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

This test measures the amount of p24 protein, a fragment of the HIV virus, in your blood. It helps track HIV progression and response to treatment.

Quick summary

["This test helps monitor HIV infection and treatment effectiveness by detecting HIV protein fragments in your blood."]

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

Key facts at a glance

LOINC
33660-2
Short code
HIV1 p24 Ag SerPl Ql Nt
Synonyms
HIV1 p24 Ag SerPl Ql Nt
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
neut
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 Is This Test Done?

Your healthcare provider may order this test if you have HIV or are at high risk for infection. It can be used to confirm HIV diagnosis, assess disease activity, or evaluate how well your treatment is working. It’s often used alongside other tests like HIV antibody tests.

What Does a Positive Result Mean?

A positive result indicates the presence of HIV p24 antigen in your blood, suggesting active HIV infection. The level can reflect how much virus is present, which may guide treatment decisions. However, results should always be interpreted by a healthcare provider in the context of other tests and clinical findings.

How Is the Sample Collected?

A blood sample is drawn from a vein, usually in your arm. The blood is then separated to obtain serum or plasma for testing.

What Are Common Results and Next Steps?

If your test is positive, your healthcare provider will likely recommend additional testing, such as HIV antibody tests, to confirm diagnosis and determine the stage of infection. If you’re already on treatment, this test may help monitor viral load over time. Results should never be interpreted alone; always discuss them with your provider.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance: Monitoring HIV Progression and Treatment Response

Short name

HIV p24 Antigen

Frequently asked questions

How often will I need this test?
The frequency depends on your treatment plan. If you’re newly diagnosed with HIV, your provider may order it more often initially. If you’re on treatment, it may be done periodically to check how well the virus is controlled. Regular follow-ups with your healthcare provider will determine the best schedule for you.
What if my test results are not within expected ranges?
If your results are outside expected ranges, it doesn’t necessarily mean there’s an issue—many factors can affect test results. Your healthcare provider will review your results with you and may recommend further testing or adjustments to your care plan based on the full clinical picture.
Can I stop taking my HIV medication if my p24 antigen levels are low?
No, you should never stop or change your HIV medication without consulting your healthcare provider. Low p24 antigen levels may indicate good control of the virus, but they don’t replace the need for ongoing treatment. Always follow your provider’s guidance to ensure safety and effectiveness.
  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