Diagnosing HIV: What to Expect with Testing

May 7th 2016

If you receive a positive test result when taking an HIV test, you can expect further testing, both to confirm the diagnosis and to establish a treatment regimen. The earlier you test for HIV after a possible infection, the more quickly you can begin treatment.

Antibody/Antigen Tests

The standard HIV test is a blood test that looks for antibodies to the HIV virus. These tests are able to detect very low levels of the HIV virus in the bloodstream and can catch the virus at its earliest stages, before the rapid HIV tests can detect it. Medical labs run these tests, known as immunoassays, and it takes several days to get the results. However, since it takes the body two to eight weeks to develop antibodies to HIV, these tests can't provide an accurate result immediately after infection.

Antigen tests are blood tests that can detect the HIV virus up to 20 days earlier than the standard antibody test because they look for antigens, which develop earlier in the blood, rather than antibodies. The Centers for Disease Control recommends these as preliminary HIV tests.

Rapid Tests

Rapid HIV tests are immunoassays that can provide results in 30 minutes. These are also done on the blood, or sometimes on urine or saliva. However, like the standard antibody test, rapid HIV tests performed during the two- to eight-week window between infection and development of antibodies can produce a false negative.

Home Tests

At-home kits test blood or saliva for the presence of HIV antibodies. These tests come in a complete kit that lets you swab the inside of your mouth or take a pinprick of blood for testing. If you choose the blood test version, you must send the blood sample to a lab for testing. Lab results are usually available within a day or so, and the purchase of the test kit includes a follow-up test if initial results are positive. All testing with one of these home kits is anonymous.

While the saliva test provides results in about 30 minutes, antibodies are only detectable in saliva about six months after infection. Saliva and oral fluid tests have a fairly high rate of false negatives. Home kits are also available to test urine for HIV.

Follow-Up Tests

If the initial diagnosis is positive, health professionals recommend an array of follow-up tests to confirm the diagnosis. The typical tests are the Western blot blood test and RNA testing.

Other follow-up tests after a positive diagnosis of HIV include a CD4 test, which needs to be repeated every three to six months, and a viral load test, which also needs regular monitoring.

Conclusion

If you think you have been exposed to the human immunodeficiency virus, or HIV, you should have an HIV test as soon as possible. Getting an HIV test is the only way to confirm whether you have HIV, the virus that causes AIDS. Early testing is vital because it allows treatment to begin right away, which in turn minimizes complications associated with HIV and AIDS. Because some tests can provide false results, and some results take a long time to achieve, there are several HIV tests available. Consult with a medical professional to choose the best test for you.

Sources

WebMD.com "Screening tests for HIV diagnosis and treatment" http://www.webmd.com/hiv-aids/hiv-aids-screening
AIDS.gov "HIV testing: Get the basics" https://www.aids.gov/hiv-aids-basics/prevention/hiv-testing/get-the-basics/
EMedicineHealth.com "HIV/AIDS testing and diagnosis" http://www.emedicinehealth.com/hivaids/page5_em.htm

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