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Lab Manual for UCSF Clinical Laboratories

Lab Manual for SFGH

Internal Resources


Item Value
Available Stat? No
Test code LVARC
Performed by? Microbiology
Sendout? No
Price range $$
In House Availability Test performed every 2 hours, 7 days a week, including holidays
Method Chemiluminescent microparticle immunoassay (CMIA) on the Abbott Architect i1000.
Interpretation NON REACTIVE results are considered final results and no further testing is performed. Specimens that test REACTIVE are reported as REACTIVE: Presumptive evidence of HIV-1 p24 Ag and/or HIV-1/2 Ab. See HIV 1/2 Antibody Differentiation assay. This supplemental assay is able to differentiate antibodies to HIV-1 and HIV-2 and is performed once a day, Monday through Saturday.

Specimens that test REACTIVE on the HIV 1/2 Ag/Ab Combo assay but NEGATIVE on the HIV 1/2 Differentiation assay could represent a false positive test or an acute infection. Submit another specimen for HIV 1/2 Ag/Ab Combo assay and a separate specimen for HIV viral load testing. HIV viral load specimens must be collected in two dedicated pearl top tubes and submitted to the laboratory within 4 hours of collection.

A REACTIVE result for the HIV-1/2 antigen/antibody test does not distinguish between the detection of HIV-1 p24 antigen, HIV-1 antibody, or HIV-2 antibody.

HIV-2 infection is very uncommon in the USA and is found principally in West Africa.

In a recent evaluation of the Architect HIV 1/2 Ag/Ab Combo Test with specimens from ZSFG and clinic patients, the overall specificity was 99.74%.
Container type Gold top gel tube, red top, or light green top gel tube (lithium heparin with gel separator)
Sample type Serum or heparinized plasma
Preferred volume 2 mL
Normal range NON REACTIVE
Synonyms Human immunodeficiency virus; HIV-1Antibody; HIV-2 Antibody; HIV-1/2 Antibody;HIV-1 p24 Antigen;
Stability 3 days at room temperature; 7 days at 4° C; -20° C is acceptable
Causes for rejection Quantity not sufficient
Turn around times 2 - 3 hours for NON REACTIVE specimens

3 - 4 hours for REACTIVE specimens
Additional information HIV-1/2 antigen/antibody testing can be requested using the Main Laboratory (2M) requisition – BLOOD/SERUM form. The Laboratory does not require a specific HIV Test Consent Form. Per ZSFG Administrative Policy 3.9, "It is the responsibility of the treating physician to obtain informed consent from the patient prior to ordering an HIV test. The treating physician should document in the medical record progress notes that the patient has given his/her informed consent or declined the HIV test."
Stat testing is not available for this test with the exception of location 6C Labor and Delivery.

HIV antigen/antibody test results must be treated as confidential information. The test result must not be released for use outside of ZSFG, or for employment or insurance purposes without specific consent by the patient. Forms for this purpose are available from the Medical Records Department. All positive results from the HIV 1/2 Ag/Ab Combo assay will be called to the PHAST team, Monday – Friday.
References 1. Centers for Disease Control and Prevention. 2014. Laboratory Testing for the Diagnosis of HIV Infection, Updated Recommendations. http://dx.doi.org/10.15620/cdc.23447.

2. Mandell GL, Bennett JE, and Dolin R., Eds. Principles and Practice of Infectious Diseases, 7th Edition, Churchill Livingstone, Inc., New York, 2010.

3. Pilcher,C., et.al., Real-world performance of the new US HIV testing algorithm in medical settings. 2015.

CPT coding 87389
Last Updated 10/17/2016 3:12:52 PM
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