| A B C D E F G H I J K L M N O P Q R S T U V W X Y Z # |
HIV Antigen Antibody 4th generation with reflex
Message| Ordering Guidelines | Tests/ Codes | |
| 1 | HIV AG AB 4th Gen with Reflex
|
HIV4G |
HIV AG AB 4th Gen with Reflex, RAPID
|
HIV4R** | |
| 2 | HIV 1_2 Differentiation with Reflex Only available as a reflex. Test performed at Quest Diagnostics. Refer to diagram 1 below. |
HIV4D Epic: not orderable. Reflex only |
| 3 | HIV 1 RNA Qual Only available as a reflex. Test performed at Quest Diagnostics. Refer to diagram 1 below. |
HIVT Epic: not orderable. Reflex only |
Test Code
HIV4G
Alias/See Also
HIV Screen, HIV4, HIV 4th Generation
Includes
Reactive specimens Reflex to HIV4D and HIVT as applicable.
Preferred Specimen
2 SST (GOLD)
Serum (Red) or Gold (SST) or Orange (OJ) or Tiger Top Serum
Serum (Red) or Gold (SST) or Orange (OJ) or Tiger Top Serum
Setup Schedule
24x7
Reference Range
Non-Reactive
Clinical Significance
HIV-1/2 Antigen/Antibody Combination Immunoassay
4th Gen HIV Testing Recommended by CDC
The CMC Laboratories now offers the initial screening test of the 4th generation HIV testing algorithm recommended by CDC. CDC recommended combined HIV antigen plus antibody screening in 2014, in part to better identify acute HIV infection. We are pleased that our Siemens Centaur instrument now supports the HIV Antigen/Antibody combination screen. If the screen is reactive, down-stream testing within the algorithm will be performed by our reference laboratory.
It is vital that providers ordering this testing remember it is a multi-part algorithm. No patient should be considered HIV-positive unless an endpoint is reached which supports a POSITIVE diagnosis. A reactive HIV Antigen/Antibody combination screen in the CRMC lab is not a positive endpoint. Preliminary Reactive screens will therefore not be phoned as critical results. See the flow chart below.
NOTE: These recommendations are intended ONLY for testing of specimens for patients aged 2 years or older because maternal antibodies against HIV might be present in uninfected infants born to HIV-infected mothers.
The information below is from CDC’s 2014 CDC’s Laboratory Testing for the Diagnosis of HIV Infection: Updated Recommendations. CMC Laboratory will follow this testing algorithm as indicated.
Overview of Testing (Refer to Diagram 1):
HIV 1_2 Antigen/Antibody Combination Immunoassay: Laboratories should conduct initial testing for HIV with an FDA-approved antigen/antibody 4th generation combination immunoassay that detects HIV-1 and HIV-2 antibodies and HIV-1 p24 antigen to screen for established infection with HIV-1 or HIV-2 and for acute HIV-1 infection. No further testing is required for specimens that are nonreactive on the initial immunoassay. Further testing will occur for specimens that are “preliminary reactive.”
(HIV4G: HIV AG/AB 4th Gen with Reflex, test available at CRMC Lab with 1-3 hour test time.)
Rationale: Initial testing with a 4th generation antigen/antibody combination immunoassay detects more acute HIV-1 infections than initial testing with a 3rd generation antibody immunoassay and identifies comparable numbers of established HIV-1 and HIV-2 infections, with comparable specificity.
HIV 1/HIV 2 Antibody Differentiation Immunoassay: Specimens with a reactive antigen/antibody combination immunoassay result should be tested with an FDA-approved antibody immunoassay that differentiates HIV-1 antibodies from HIV-2 antibodies. Reactive results on the initial antigen/antibody combination immunoassay and the HIV-1/HIV-2 antibody differentiation immunoassay should be interpreted as positive for HIV-1 antibodies, HIV-2 antibodies, or HIV-1 and HIV-2 antibodies.
(HIV 1/HIV2 Antibody differentiation will be done at Quest Lab with 1 to 3 days test time)
Rationale: Use of the HIV-1/HIV-2 antibody differentiation assay after a reactive initial 4th generation HIV-1/HIV-2 antibody immunoassay detects HIV-1 antibodies earlier than the HIV-1 Western blot, reduces indeterminate results, and identifies HIV-2 infections. Turnaround time for test results is shorter and the cost is lower for the HIV-1/HIV-2 antibody differentiation assay compared with the HIV-1 Western blot. Available evidence is insufficient to recommend specific additional testing, without clinical follow-up, for specimens that are dually reactive for HIV-1 and HIV-2 antibodies on the differentiation immunoassay.
HIV-1 NAT Test: Specimens that are reactive on the initial antigen/antibody combination immunoassay and nonreactive or indeterminate on the HIV-1/HIV-2 antibody differentiation immunoassay should be tested with an FDA-approved HIV-1
NAT.
(HIV 1 NAT testing will be done at Quest lab with 3 to 7 days test time.)
• A positive HIV-1 NAT result indicates evidence for acute HIV-1 infection.
• A negative HIV-1 NAT result indicates HIV-1 infection is unlikely. Consider testing for HIV-2 DNA if clinically indicated.
Rationale: HIV-1 NAT results can distinguish acute HIV-1 infection from false-positive initial immunoassay results in specimens with a reactive antigen/antibody immunoassay and a nonreactive HIV-1/HIV-2 antibody differentiation assay result. HIV-1 NAT does not detect HIV-2, and no HIV-2 NAT is FDA approved, however, HIV-2 testing may be available through the CDC.
4th Gen HIV Testing Recommended by CDC
The CMC Laboratories now offers the initial screening test of the 4th generation HIV testing algorithm recommended by CDC. CDC recommended combined HIV antigen plus antibody screening in 2014, in part to better identify acute HIV infection. We are pleased that our Siemens Centaur instrument now supports the HIV Antigen/Antibody combination screen. If the screen is reactive, down-stream testing within the algorithm will be performed by our reference laboratory.
It is vital that providers ordering this testing remember it is a multi-part algorithm. No patient should be considered HIV-positive unless an endpoint is reached which supports a POSITIVE diagnosis. A reactive HIV Antigen/Antibody combination screen in the CRMC lab is not a positive endpoint. Preliminary Reactive screens will therefore not be phoned as critical results. See the flow chart below.
NOTE: These recommendations are intended ONLY for testing of specimens for patients aged 2 years or older because maternal antibodies against HIV might be present in uninfected infants born to HIV-infected mothers.
The information below is from CDC’s 2014 CDC’s Laboratory Testing for the Diagnosis of HIV Infection: Updated Recommendations. CMC Laboratory will follow this testing algorithm as indicated.
Overview of Testing (Refer to Diagram 1):
HIV 1_2 Antigen/Antibody Combination Immunoassay: Laboratories should conduct initial testing for HIV with an FDA-approved antigen/antibody 4th generation combination immunoassay that detects HIV-1 and HIV-2 antibodies and HIV-1 p24 antigen to screen for established infection with HIV-1 or HIV-2 and for acute HIV-1 infection. No further testing is required for specimens that are nonreactive on the initial immunoassay. Further testing will occur for specimens that are “preliminary reactive.” (HIV4G: HIV AG/AB 4th Gen with Reflex, test available at CRMC Lab with 1-3 hour test time.)
Rationale: Initial testing with a 4th generation antigen/antibody combination immunoassay detects more acute HIV-1 infections than initial testing with a 3rd generation antibody immunoassay and identifies comparable numbers of established HIV-1 and HIV-2 infections, with comparable specificity.
HIV 1/HIV 2 Antibody Differentiation Immunoassay: Specimens with a reactive antigen/antibody combination immunoassay result should be tested with an FDA-approved antibody immunoassay that differentiates HIV-1 antibodies from HIV-2 antibodies. Reactive results on the initial antigen/antibody combination immunoassay and the HIV-1/HIV-2 antibody differentiation immunoassay should be interpreted as positive for HIV-1 antibodies, HIV-2 antibodies, or HIV-1 and HIV-2 antibodies. (HIV 1/HIV2 Antibody differentiation will be done at Quest Lab with 1 to 3 days test time)
Rationale: Use of the HIV-1/HIV-2 antibody differentiation assay after a reactive initial 4th generation HIV-1/HIV-2 antibody immunoassay detects HIV-1 antibodies earlier than the HIV-1 Western blot, reduces indeterminate results, and identifies HIV-2 infections. Turnaround time for test results is shorter and the cost is lower for the HIV-1/HIV-2 antibody differentiation assay compared with the HIV-1 Western blot. Available evidence is insufficient to recommend specific additional testing, without clinical follow-up, for specimens that are dually reactive for HIV-1 and HIV-2 antibodies on the differentiation immunoassay.
HIV-1 NAT Test: Specimens that are reactive on the initial antigen/antibody combination immunoassay and nonreactive or indeterminate on the HIV-1/HIV-2 antibody differentiation immunoassay should be tested with an FDA-approved HIV-1NAT.
(HIV 1 NAT testing will be done at Quest lab with 3 to 7 days test time.)
• A positive HIV-1 NAT result indicates evidence for acute HIV-1 infection.
• A negative HIV-1 NAT result indicates HIV-1 infection is unlikely. Consider testing for HIV-2 DNA if clinically indicated.
Rationale: HIV-1 NAT results can distinguish acute HIV-1 infection from false-positive initial immunoassay results in specimens with a reactive antigen/antibody immunoassay and a nonreactive HIV-1/HIV-2 antibody differentiation assay result. HIV-1 NAT does not detect HIV-2, and no HIV-2 NAT is FDA approved, however, HIV-2 testing may be available through the CDC.
Performing Laboratory
CRMC Laboratory
