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Test Catalog

Test ID: HIVDX    
HIV-1 and HIV-2 Antigen and Antibody Diagnostic Evaluation, Plasma

Useful For Suggests clinical disorders or settings where the test may be helpful

Diagnosing HIV-1 and/or HIV-2 infection in symptomatic patients more than 2 years old

 

Follow-up testing of individuals with reactive rapid HIV test results

 

This test is not offered as a screening or confirmatory test for blood donor specimens.

Testing Algorithm Delineates situations when tests are added to the initial order. This includes reflex and additional tests.

This test begins with HIV-1/-2 antigen and antibody screen by chemiluminescence immunoassay. If the screen result is reactive, then HIV-1/-2 antibody differentiation test by immunochromatographic method is performed at an additional charge.

If HIV-1/-2 antibody differentiation is negative for both HIV-1 antibody and HIV-2 antibody, or indeterminate/negative for HIV-1/HIV-2 antibody, or indeterminate/indeterminate for HIV-1/ HIV-2 antibody, then the HIV-1 RNA detection and quantification is performed at an additional charge.

 

The following algorithms are available in Special Instructions:

-HIV Testing Algorithm (Fourth-Generation Screening Assay), Including Follow-up of Reactive Rapid Serologic Test Results

-Meningitis/Encephalitis Panel Algorithm

Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test

AIDS is caused by 2 known types of HIV. HIV type 1 (HIV-1) is found in patients with AIDS, AIDS-related complex, and asymptomatic infected individuals at high risk for AIDS. The virus is transmitted by sexual contact, by exposure to infected blood or blood products, or from an infected mother to her fetus or infant. HIV type 2 (HIV-2) infection is endemic only in West Africa, and it has been identified in individuals who had sexual relations with individuals from that geographic region. HIV-2 is similar to HIV-1 in viral morphology, overall genomic structure, and its ability to cause AIDS.

 

Antibodies against HIV-1 and HIV-2 are usually not detectable until 6 to 12 weeks following exposure and are almost always detectable by 12 months. They may fall to undetectable levels (ie, seroreversion) in the terminal stage of AIDS when the patient's immune system is severely depressed.

 

Routine serologic screening of patients at risk for HIV-1 or HIV-2 infection usually begins with a HIV-1/-2 antigen and/or antibody screening test, which may be performed by various FDA-approved assay methods, including rapid HIV antibody tests, enzyme immunoassays, and chemiluminescent immunoassays. In testing algorithms that begin with these methods, supplemental or confirmatory testing should be requested only for specimens that are repeatedly reactive by these methods.

Reference Values Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.

Negative

Interpretation Provides information to assist in interpretation of the test results

Negative HIV-1/-2 antigen and antibody screening test results usually indicate the absence of HIV-1 and HIV-2 infection. However, such negative results do not rule-out acute HIV infection. If acute HIV-1 infection is suspected, it is recommended that a specimen be submitted for detection of HIV-1 RNA (HIVQN / HIV-1 RNA Detection and Quantification, Plasma) or HIV-1 DNA and RNA (HIVP / HIV-1 DNA and RNA Qualitative Detection by PCR, Plasma).

 

Reactive HIV-1/-2 antigen and antibody screening test results suggest the presence of HIV-1 and/or HIV-2 infection, but it is not diagnostic for HIV infection and should be considered preliminary. Reactive result of this assay does not differentiate among reactivity with HIV-1 p24 antigen, HIV-1 antibody, and HIV-2 antibody. Diagnosis of HIV infection must be based on results of supplemental tests, such as HIV antibody confirmation/differentiation test (automatically reflexed on all samples with reactive screen test results at an additional charge).

 

All initially positive supplemental or confirmatory HIV test results (by serologic or molecular test methods) should be verified by submitting a second serum specimen for repeat testing. Such positive HIV test results are required under laws in many states in the United States to be reported to the departments of health of the respective states where the patients reside.

 

See HIV Testing Algorithm (Fourth-Generation Screening Assay), Including Follow-up of Reactive Rapid Serologic Test Results in Special Instructions.

Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances

Reactive result of this assay does not differentiate among reactivity with HIV-1 p24 antigen, HIV-1 antibody, and HIV-2 antibody.

 

A reactive screening test result is not diagnostic for HIV infection and should be considered preliminary.

 

The positive predictive value of a reactive screening test result is highly dependent on the prevalence of HIV infection in the population tested. The lower the prevalence of HIV infection, the lower the positive predictive value and higher the false-positive rate of the test. Diagnosis of HIV infection must be based on positive results of the supplemental or confirmatory serologic or molecular tests.

 

Recipients of experimental HIV-1 vaccines may have false-reactive HIV antibody test results due to the presence of vaccine-induced, HIV-1-specific antibodies without actual HIV infection.

 

Negative serologic or molecular HIV screening test results should be evaluated with caution in patients with clinical symptoms and/or a history of high-risk behavior for HIV infection. Repeat testing in 1 to 2 months is recommended in these at-risk individuals.

 

Assay performance characteristics have not been established for the following specimen characteristics:

-Grossly hemolyzed (hemoglobin level of >500 mg/dL)

-Grossly lipemic (triolein level of >1250 mg/dL)

-Grossly icteric (total bilirubin level of >20 mg/dL)

-Heat-inactivated specimens

-Cadaveric specimens

-Presence of particulate matter

Clinical Reference Recommendations for in-depth reading of a clinical nature

1. Chavez P, Wesolowski L, Patel P, et al: Evaluation of the performance of the Abbott ARCHITECT HIV Ag/Ab Combo assay. J Clin Virol. 2011;52(Suppl 1):S51-S55

2. Branson BM, Owen SM, Wesolowski LG, et al: Laboratory testing for the diagnosis of HIV infection: Updated recommendations. Centers for Disease Control and Prevention; June 27, 2014. Available at http://stacks.cdc.gov/view/cdc/23447

3. Centers for Disease Control and Prevention: 2018 Quick reference guide: Recommended laboratory HIV testing algorithm for serum or plasma specimens. CDC; January 2018. Available at https://stacks.cdc.gov/view/cdc/50872

4. Centers for Disease Control and Prevention. Technical update: Use of the Determine HIV 1/2 Ag/Ab combo test with serum or plasma in the laboratory algorithm for HIV diagnosis. CDC; October 4, 2017. Available at https://stacks.cdc.gov/view/cdc/48472

Special Instructions Library of PDFs including pertinent information and forms related to the test