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HIV Antibody

Also known as: AIDS test; AIDS screen; HIV serology
Formal name: Human immunodeficiency virus antibody test
Related tests: p24 antigen test; CD4 and CD8; HIV viral load; HIV genotypic resistance testing

At a Glance

Why Get Tested?

To determine if you are infected with Human immunodeficiency virus (HIV)

When to Get Tested?

One month to three months after you think you may have been exposed to the virus; the average time for the antibody to be detected is two weeks after exposure to the virus

Sample Required?

A blood sample collected from a vein in your arm; there are also tests available that can be performed on urine and/or oral fluid

Test Preparation Needed?

None

The Test Sample

What is being tested?

This test detects HIV antibodies in blood or other body fluids. HIV, human immunodeficiency virus, is the virus that causes AIDS (acquired immunodeficiency syndrome), which destroys the immune system and leaves the body vulnerable to debilitating infections. When HIV enters the body, such as through contact with an infected individual or contaminated needle, the immune system responds by producing antibodies directed against the virus. These antibodies can be detected about 3 to 8 weeks after exposure to the virus. If exposure to the virus is more recent, then antibody levels may be too low to detect. It may be necessary to perform a p24 antigen test or an HIV RNA (viral load) test in order to detect the virus.

How is the sample collected for testing?

A blood sample is obtained by inserting a needle into a vein in the arm. There also are tests available that can be performed on urine or oral samples. An oral sample is obtained by using a special small, spatula-like device with a flat pad on the end. The flat pad is placed above the teeth against the outer gum and is swabbed completely once around the outer part of the upper and lower gums.

NOTE: If undergoing medical tests makes you or someone you care for anxious, embarrassed, or even difficult to manage, you might consider reading one or more of the following articles: Coping with Test Pain, Discomfort, and Anxiety, Tips on Blood Testing, Tips to Help Children through Their Medical Tests, and Tips to Help the Elderly through Their Medical Tests.

Another article, Follow That Sample, provides a glimpse at the collection and processing of a blood sample and throat culture.

Is any test preparation needed to ensure the quality of the sample?

No test preparation is needed.

The Test

How is it used?

HIV antibody testing is used to screen for and diagnose HIV infections. Early treatment of HIV infection and immune system monitoring can greatly improve long-term health. Also, knowing your HIV status may help you change behaviors that would put you and others at risk.

Antibodies to the HIV virus are often detected by a screening test called an ELISA. The ELISA test is repeated if positive. The ELISA method is very sensitive but requires another test, a Western Blot, to confirm the results because false positives can occur. These tests can be done on blood, urine or oral sample in a doctor’s office or a local clinic. There are several rapid tests available in which results are generated in about 20 minutes. However, these too must have confirmatory testing before a final diagnosis can be made.

There is also a home collection kit approved by the US Food and Drug Administration (FDA) that is available for HIV antibody testing. This allows you to take a sample of your blood from a finger at home and mail it to a testing center. You would then hear your results later over the phone, along with appropriate counseling. There are, however, no available tests that can be performed at home. (For more, see the article on Home Testing and the FDA webpage on HIV home tests.)

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When is it ordered?

Several organizations, including the Centers for Disease Control (CDC), American College of Physicians (ACP), and HIV Medicine Association (HMA) recommend that anyone over the age of 13 be screened for HIV.

Antibody testing for HIV is especially important if you are in a high risk group or if you think you may have been exposed to HIV. Testing is recommended if:

  • You are sexually active (three or more sexual partners in the last 12 months).
  • You received a blood transfusion prior to 1985, or a sexual partner received a transfusion and later tested positive for HIV. For more information, see the CDC webpage How safe is the blood supply in the US?
  • You are uncertain about your sexual partner’s risk behaviors.
  • You are a male who has had sex with another male.
  • You have used street drugs by injection, especially when sharing needles and/or other equipment.
  • You have a sexually transmitted disease (STD).
  • You are a health care worker with direct exposure to blood on the job.
  • You are pregnant. (There are now treatments that can greatly reduce the risk that a pregnant woman who has HIV will give the virus to her baby.)
  • You are a woman who wants to make sure you are not infected with HIV before getting pregnant (see Pregnancy: Pre-conception, HIV).

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What does the test result mean?

A healthy individual has no antibodies to HIV. However, a negative screening test means only that there is no evidence of disease at the time of the test. It is important for those who are at increased risk of HIV infection to have screening tests performed on a regular basis to check for possible exposure to the virus.

If you test positive for HIV antibodies on both the ELISA and the Western Blot tests, you are considered to be infected with HIV. HIV cannot be cured, but early diagnosis allows for treatment that can help to suppress levels of virus in your body (viral load) and slow progression of the disease.

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Is there anything else I should know?

Antibody testing will not detect HIV immediately after exposure, during the window before the development of antibodies. If you are tested too soon, your result may be negative despite the fact that you are infected (false negative). In this case, you may be tested using a p24 antigen test that can detect actual viral protein in the blood 1 to 3-4 weeks after exposure or an HIV RNA test (viral load) that detects the presence of the virus, not the antibody response to it. Or you should have another HIV antibody test in 3–6 months from the time of a possible exposure to the virus.

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Common Questions

1.  What are the symptoms of HIV infection?

The only reliable way to tell if you are infected with HIV is to get tested. This is because many people with HIV do not experience symptoms for years after the initial infection or have symptoms that are very similar to symptoms of other illnesses. See this CDC web page: HIV/AIDS Basics - Questions and Answers.

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2.  When does AIDS develop?

Symptoms of the initial HIV infection can mimic those of influenza and other viral infections. The term AIDS applies to the most advanced stages of HIV infection. According to the CDC, AIDS is diagnosed when your CD4 T-cell count drops below 200 cells per cubic millimeter of blood or when you have HIV and an AIDS-related illness such as tuberculosis. For more information, see this article from CDC's MMWR.

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3.  What are the treatments for HIV/AIDS?

Currently, there is no cure for HIV or AIDS. However, there are therapies that can help. The CDC’s booklet, Living with HIV/AIDS, is available online. The FDA also offers an online list of FDA-approved therapies. Early treatment is recommended.

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4.  Should I tell anyone else of my test results?

Yes. If you test positive for HIV, it is important that you tell your health care providers as well as all current and future sex partners and/or anyone with whom you share needles. Counseling services are often available from the clinic that performed the test or from your health care provider that will help you to inform the people who need to know.

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5.  How confidential are HIV test results?

Your HIV status, like other medical conditions and test results, is protected by the HIPAA Privacy Rule and cannot be shared with friends, family, or employers without your written permission. Your HIV status may be shared with your health care providers who have a “need to know” in order to treat you. Also, in order to determine the incidence of HIV and to provide appropriate prevention and care services, all new cases of HIV are reported to state and local health departments.

Certain testing centers provide either anonymous (your name is never given) or confidential (your name is given but kept private) HIV testing and counseling. The FDA has approved one home testing device that allows you to remain anonymous and to get confidential results. You can also contact your state, county, or city health department to find out where testing may be available.

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6.  Can you use the HIV antibody test to detect HIV in newborns?

No. Because maternal antibodies are transferred from mother to baby and stay in the newborn’s system for 6–12 months, a different test must be used. This test is called the HIV DNA test (see FAQ #2).

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7.  Are there HIV testing methods other than a blood test?

Yes. Methods that test either oral fluid or urine are available in some locations. This CDC web page has more information on the different types of HIV screening tests available in the U.S.

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Article Sources

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NOTE: This article is based on research that utilizes the sources cited here as well as the collective experience of the Lab Tests Online Editorial Review Board. This article is periodically reviewed by the Editorial Board and may be updated as a result of the review. Any new sources cited will be added to the list and distinguished from the original sources used.

Sources Used in Current Review

Pagana, Kathleen D. & Pagana, Timothy J. (© 2007). Mosby’s Diagnostic and Laboratory Test Reference 8th Edition: Mosby, Inc., Saint Louis, MO. Pp. 23-27.

Clarke, W. and Dufour, D. R., Editors (2006). Contemporary Practice in Clinical Chemistry, AACC Press, Washington, DC. Pp. 487-490.

Bennett, N. and Rose, F. (2008 October 22, Updated). HIV Disease. eMedicine [On-line information]. Available online at http://www.emedicine.com/med/TOPIC24.HTM through http://www.emedicine.com. Accessed on 10/26/08.

Mayo Clinic Staff (2008 August 9). MayoClinic HIV/AIDS. MayoClinic.com [On-line information]. Available online at http://www.mayoclinic.com/health/hiv-aids/DS00005 through http://www.mayoclinic.com. Accessed on 10/30/08.

(2005 November, Revised). Human Immunodeficiency Virus (HIV) Introduction. Merck Manual for Healthcare Professionals [On-line information]. Available online at http://www.merck.com/mmpe/sec14/ch192/ch192a.html?qt=HIV&alt=sh through http://www.merck.com. Accessed on 10/30/08.

(2008 September, Reviewed). Human Immunodeficiency Virus – HIV. ARUP Consult [On-line information]. Available online at http://www.arupconsult.com/Topics/InfectiousDz/Viruses/HIV.html through http://www.arupconsult.com. Accessed on 10/30/08.

(2006 September 22). Revised Recommendations for HIV Testing of Adults, Adolescents, and Pregnant Women in Health-Care Settings. CDC MMWR 55(RR14); 1-17 [On-line information]. Available online at http://www.cdc.gov/mmwr/preview/mmwrhtml/rr5514a1.htm through http://www.cdc.gov. Accessed on 11/1/08.

(January 29, 2009) OraSure Technologies. Oral Fluid—Specimen Collection and Testing Procedures. P. 4. PDF available for download at http://www.orasure.com/uploaded/400.pdf through http://www.orasure.com. Accessed February 2009.

Sources Used in Previous Reviews

Thomas, Clayton L., Editor (1997). Taber’s Cyclopedic Medical Dictionary. F.A. Davis Company, Philadelphia, PA [18th Edition].

Pagana, Kathleen D. & Pagana, Timothy J. (2001). Mosby’s Diagnostic and Laboratory Test Reference 5th Edition: Mosby, Inc., Saint Louis, MO.

Janice K. Pinson MT, MBA. Molecular Business Strategies, Birmingham, MI.