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HIV p24 Antigen Quantitative Serum

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

This test measures the amount of p24 protein in your blood, which is produced by the HIV virus. It helps track HIV infection progression and response to treatment.

Quick summary

["This test helps monitor HIV levels in your body over time."]

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

Key facts at a glance

LOINC
9821-0
Short code
HIV1 p24 Ag Ser Ql
Synonyms
HIV1 p24 Ag Ser Ql
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
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 to check if HIV is active in your body, monitor how your treatment is working, or evaluate your overall health during HIV treatment. It can also be used during early stages of infection when antibodies may not yet be detectable.

What Does a Positive Result Mean?

A positive result indicates the presence of HIV p24 antigen, meaning the virus is actively replicating in your system. This suggests HIV is present and may be progressing. Your doctor will discuss next steps, such as adjusting treatment or further testing.

What Does a Negative Result Mean?

A negative result means no detectable p24 antigen was found in your serum, which may mean the virus is not actively producing this protein at the time of testing. However, HIV can still be present in your body, so ongoing monitoring is important.

How Is This Test Performed?

A blood sample is drawn from a vein, typically in your arm. The sample is then processed and analyzed in a lab using immunoassay methods to detect the p24 antigen.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance: This test is particularly useful for individuals with early HIV infection, those who are newly diagnosed, or those who may not yet have developed detectable antibodies. It complements other HIV tests, such as antibody tests, by providing a direct measurement of the virus’s presence.

Short name

HIV p24 Antigen

Frequently asked questions

How often should I expect this test?
The frequency depends on your medical needs. Your healthcare provider will determine how often you need this test based on your treatment plan, overall health, and whether you’re experiencing symptoms of HIV progression.
What are the possible side effects of this blood draw?
Most people experience only minor discomfort or bruising at the injection site. Rarely, there may be mild swelling or redness. If you experience excessive pain, bleeding, or signs of infection (like increased redness or warmth), contact your healthcare provider.
Can this test be done at home?
No, this test requires a blood sample collected by a healthcare professional in a clinical setting. It cannot be performed at home.
  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