Laboratory testing plays a central role in the spectrum of clinical care for patients with human immunodeficiency virus (HIV) infection. This Test Guide provides an overview of the use of laboratory tests in the screening, diagnosis, and management of HIV infection based on clinical practice guidelines (Table 1).

Table 1. Clinical Practice Guidelines for Diagnosis and Management of HIV Infectiona

Organization	Guideline title	Guideline link
USPSTF	Screening for HIV infection1	USPreventiveServicesTaskForce.org/USPSTF/Recommendation/Human-Immunodeficiency-Virus-HIV-Infection-Screening
CDC	Laboratory testing for the diagnosis of HIV infection: updated recommendations2	Stacks.CDC.gov/View/CDC/23447
CDC	Recommended laboratory HIV testing algorithm for serum or plasma specimens3	Stacks.CDC.gov/View/CDC/50872
DHHS	Guidelines for the use of antiretroviral agents in adults and adolescents with HIV4	ClinicalInfo.HIV.gov/en/Guidelines/HIV-Clinical-Guidelines-Adult-and-Adolescent-arv/Whats-New-Guidelines
DHHS	Guidelines for the use of antiretroviral agents in pediatric HIV infection5	ClinicalInfo.HIV.gov/en/Guidelines/Pediatric-arv/Whats-New-Guidelines
DHHS	Recommendations for the use of antiretroviral drugs during pregnancy and interventions to reduce perinatal HIV transmission in the United States6	ClinicalInfo.HIV.gov/en/Guidelines/Perinatal/Whats-New-Guidelines
HIVMA/IDSA	Primary care guidance for persons with human immunodeficiency virus: 2020 update by the HIV Medicine Association of the Infectious Diseases Society of America7	IDSociety.org/Practice-Guideline/Primary-Care-Management-of-People-With-HIV

CDC, Centers for Disease Control and Prevention; DHHS, US Department of Health and Human Services; HIVMA/IDSA, HIV Medicine Association of the Infectious Diseases Society of America; USPSTF, US Preventive Services Task Force.
a	This listing is not intended to be comprehensive. Additional guideline statements for HIV infection are available from DHHS and other organizations.

 

This information is provided for informational purposes only and is not intended as medical advice. A physician’s test selection and interpretation, diagnosis, and patient management decisions should be based on their education, clinical expertise, and assessment of the patient. For additional information on laboratory testing for HIV infection, please see the following educational guides available from Quest Diagnostics:

• HIV Pre-exposure Prophylaxis (PrEP): Laboratory Testing (TestDirectory.QuestDiagnostics.com/Test/Test-Guides/TG_HIV_PrEP_Panels/)
• HIV-1/2 Antigen and Antibodies, Fourth Generation, With Reflexes (TestDirectory.QuestDiagnostics.com/Test/Test-Guides/TS_HIV4thGenScreen/)
• HIV-1 Genotype (TestDirectory.QuestDiagnostics.com/Test/Test-Guides/TS_HIV-1_Genotype/)
• HIV-1 Resistance, Proviral DNA (RTI, PI, Integrase Inhibitors) (TestDirectory.QuestDiagnostics.com/Test/Test-Guides/TS_HIV_Resistance_Proviral/)

Screening and diagnosis

The US Preventive Services Task Force (USPSTF) recommends voluntary, opt-out HIV screening for all adolescents and adults between 15 and 65 years of age.1 Screening is also recommended for all pregnant persons (and their partners, if HIV status is unknown) and for persons under 15 or older than 65 years of age who are at higher risk for HIV infection.1,5,6 The USPSTF considers repeat screening to be reasonable for those at high risk for infection but does not specify an optimal frequency.1 However, the Centers for Disease Control and Prevention (CDC) recommends screening those at high risk at least annually.8

Tests offered by Quest for HIV screening and diagnosis can be found in Table 2.

"Fourth-generation" testing algorithm

The 2014 HIV diagnostic testing algorithm recommended by the CDC is based on newer tests that are more sensitive for acute infection.2,3 The algorithm is designed to (1) detect acute infections more often; (2) reduce the frequency of indeterminate results on supplemental testing; and (3) differentiate HIV-1 and HIV-2 (HIV-1/2) antibodies.2,9

HIV antibodies and p24 antigen

The “fourth-generation” testing algorithm begins with a screening test for HIV-1/2. The screening test of choice is a “fourth-generation” combination assay that detects HIV-1/2 antibodies and/or HIV-1 p24 antigen.2,3 HIV p24 antigen becomes detectable before seroconversion but rapidly disappears thereafter. Thus, the antigen component allows detection of infection during a portion of the pre-seroconversion window period, while the antibody component allows detection post-seroconversion. “Fourth-generation” assays can detect acute infection a median of 5 to 7 days before “third-generation” antibody-only detection assays.2,10 These antigen/antibody (Ag/Ab) combination assays have >99.7% sensitivity and >99.5% specificity for HIV infection2 and identify most (>80%) acute infections that would otherwise require nucleic acid testing for detection.10 Repeatedly reactive Ag/Ab screening assay results require confirmation with a supplemental antibody immunoassay that differentiates between HIV-1 and HIV-2 antibodies.2,3

HIV-1/2 differentiation has important treatment implications, as HIV-2 does not respond to some antiretroviral agents used for HIV-1 treatment. Additionally, these assays can detect HIV antibodies earlier and have a faster turnaround time than the previously utilized Western blot methodology.2 Results are interpreted as positive for HIV-1, positive for HIV-2 (with or without HIV-1 cross-reactivity), positive for HIV (untypable), negative for HIV, or indeterminate for HIV-1 and/or HIV-2. A positive result confirms the presence of HIV-1 and/or HIV-2 antibodies, whereas negative or indeterminate results for HIV-1/2 prompt confirmation by HIV-1 RNA testing.2,3

HIV-1 RNA, qualitative

HIV-1 RNA can be detected approximately 10 days after exposure and 4 to 10 days before p24 antigen and 10 to 13 days before HIV antibody.2 Therefore, ultrasensitive nucleic acid amplification-based testing (NAAT) is useful for detecting suspected infection soon after exposure. “Detected” HIV-1 RNA results indicate acute infection when HIV-1/2 antibodies are negative or indeterminate; “not detected” HIV-1 RNA results are consistent with the absence of HIV-1 infection when HIV-1 antibodies are negative or indeterminate. “Not detected” HIV-1 RNA results may be followed with an HIV-2 DNA/RNA test if clinically warranted.2,3 When NAAT is used to diagnose acute infection, subsequent seroconversion should be documented.2,10

Infection in newborns

HIV-1 testing is also useful for detecting HIV-1 infection in infants at risk of perinatal HIV infection (eg, those born to persons with HIV infection).5,6 Guidelines recommend virologic testing (ie, HIV-1 RNA or DNA NAAT) for all perinatally-exposed, non-breastfed infants at 14 to 21 days, 1 to 2 months, and 4 to 6 months of age.5,6 Infants at high risk of perinatal HIV infection (eg, born to persons with HIV who received inadequate antiretroviral therapy [ART] during pregnancy) should also be tested at birth before initiating ART and 2 to 6 weeks after ART is discontinued.5,6

Breastfeeding is not recommended for people with HIV in the United States.5,6 Infants born to those who opt to breastfeed should be tested at birth and at 14 to 21 days, 1 to 2 months, and 4 to 6 months of age. Further testing is recommended every 3 months while breastfeeding and at 4 to 6 weeks, 3 months, and 6 months after breastfeeding is discontinued.5,6

Antibody-based testing is not appropriate in infants younger than 18 months, as maternal antibodies can cross the placenta and be detected in the infant after birth. In addition, testing for p24 antigen is not recommended for infants because it has low sensitivity relative to other virologic assays in the early months after birth.5,6 Instead, qualitative HIV-1 RNA or DNA PCR assays can be used for initial testing. For infants at risk of non-subtype B or Group O HIV-1 infection, an RNA or dual DNA/RNA assay should be used instead of a DNA assay. Positive results need to be confirmed with a repeat virologic test on a second specimen.5,6

Table 2. Laboratory Tests Used for Screening and Diagnosis of HIV Infection

Test code	Test name	Primary clinical use and/or differentiating factors
91431	HIV-1/2 Antigen and Antibodies, Fourth Generation, With Reflexesa Includes HIV-1/2 antigen and antibody with reflex to HIV-1/2 antibody differentiation; if differentiation test is indeterminant or negative, reflex to HIV-1 RNA.	Screen for and confirm HIV-1 and HIV-2 infection, including acute infection; uses “fourth-generation” screening immunoassay; reflexes are consistent with the 2014 CDC HIV diagnostic algorithm3
8401	HIV-1 DNA, Qualitative, PCRb	Detect HIV-1 infection in infants up to 18 months of age; qualitative HIV-1 DNA test detects HIV-1 proviral DNA
34977	HIV-2 DNA/RNA, Qualitative, Real-Time PCRc	Follow-up evaluation of negative results on confirmatory HIV-1 RNA testing, when clinically indicated2,3
16185	HIV-1 RNA, Qualitative, Real-Time PCR	Detect HIV-1 infection, including acute infection; confirm HIV-1 infection in individuals with repeatedly reactive initial results, including those with nonreactive HIV antibody–based supplemental test results; detect HIV-1 infection in infants up to 18 months of age

a	Reflex tests are performed at an additional charge and are associated with an additional CPT code(s).
b	This test was performed using a kit that has not been cleared or approved by the FDA. The analytical performance characteristics of this test have been determined by Quest. This test should not be used for diagnosis without confirmation by other medically established means.
c	This test was developed and its analytical performance characteristics have been determined by Quest. It has not been cleared or approved by the US Food and Drug Administration. This assay has been validated pursuant to the CLIA regulations and is used for clinical purposes.

 

Management

This section provides a brief overview of tests used in the management of HIV infection in conjunction with ART, which is recommended for all patients with HIV infection (Figure).4,7

Monitoring immune status and viral load

Lymphocyte subset testing (CD4 count)

The CD4+ T-cell (CD4) count is the most valuable indicator of immune status and the strongest predictor of disease progression and survival in patients with HIV infection.4 CD4 counts should be measured in all patients with HIV infection at entry into care and every 3 to 6 months in patients who do not immediately begin ART.4 Baseline CD4 count provides an indication of the urgency of beginning ART and helps determine whether to initiate prophylaxis for opportunistic infections.4

The CD4 count should be measured 3 months after beginning ART to help assess immunologic response and the need to initiate or discontinue treatment for opportunistic infections.4 CD4 count should then be monitored every 3 months if counts are <300 cells/mm3 and every 6 months if ≥300 cells/mm3. After 2 years of ART, CD4 counts can be monitored less frequently (every 12 months) in stable patients with counts consistently between 300 and 500 cells/mm3 and suppressed viremia; continued CD4 monitoring is optional if counts are consistently >500 cells/mm3. If counts remain <300 cells/mm3 after 2 years of ART but viremia is consistently suppressed, less frequent monitoring (every 6 months) can also be considered.4 More frequent monitoring should occur as clinically indicated, such as the initiation of treatment known to reduce CD4 count (eg, corticosteroids or antineoplastic agents). Monitoring CD4 counts every 3 to 6 months is recommended for patients receiving ART who do not maintain viral suppression.4

CD4 counts can exhibit substantial variation and may be affected by medications, intercurrent illnesses, diurnal variation, and other factors.4,7,11 The trend in CD4 counts is more important than any single value; a 30% or greater change in the absolute CD4 count between tests, or a 3-percentage point or greater change in the CD4 percentage, is considered clinically significant.4

HIV-1 RNA, quantitative (viral load)

HIV-1 viral load is the primary marker of ART effectiveness. Before treatment initiation, the viral load provides information on the risk of disease progression, informs selection of an initial treatment regimen, and establishes a baseline for assessing treatment response.4 After treatment is initiated, a primary goal is to decrease the viral load below the limits of detection (LODs) of the available assays within 24 weeks.4 Thereafter, measuring viral load helps assess the continuing effectiveness of therapy. A viral load ≥200 copies/mL on 2 successive specimens indicates antiviral virologic failure.4

The recommended frequency of viral load testing depends on the stage of disease management4:

• Entry into care/prior to treatment initiation: test at the time of diagnosis; repeat testing is optional in patients not initiating treatment
• Start of treatment: test immediately prior to initiation of treatment and within 4 to 8 weeks after treatment initiation; test every 4 to 8 weeks thereafter until viral load decreases below the level of detection (generally <20 copies/mL) or is suppressed to <50 copies/mL
• Change in regimen because of virologic failure: test before change and within 4 to 8 weeks after change; test every 4 to 8 weeks thereafter until viral load is suppressed below the level of detection or <50 copies/mL
• Change in regimen because of treatment toxicity or regimen simplification: test within 4 to 8 weeks after change to assess the effectiveness of the new regimen
• Continuing therapy/stable antiretroviral regimen: test every 3 to 4 months or when there is a clinical event; consider extending the interval to every 6 months for patients who adhere to therapy (and are not at risk of nonadherence) and exhibit long-term suppression of viral load (>1 year) and stable immunologic status

Quest offers an FDA-cleared HIV-1 real-time polymerase chain reaction (PCR) assay for quantitation of HIV-1 RNA in blood plasma (Table 3). A change in viral load of 3-fold (0.5 log10 copies/mL) or greater is considered clinically significant.4

Table 3. Laboratory Tests Used for Monitoring HIV-1 Infection

Test code	Test name		Primary clinical use and/or differentiating factors
Lymphocyte subset testing
8360	Lymphocyte Subset Panel 5 Includes absolute lymphocyte count, absolute CD4, and percentage CD4.		Monitor urgency of therapy initiation; monitor cellular immunocompetence
HIV-1 viral load testing
34471	HIV-1 RNA, Quantitative, PCR With Reflex to Genotypea Includes reflex to HIV-1 Genotype if HIV-1 RNA is ≥400 copies/mL.		Evaluate prognosis; assess effectiveness of ART and need to switch treatment regimen. See Table 4 for clinical use of genotypic assays.
40085	HIV-1 RNA, Quantitative, Real-Time PCR		Evaluate prognosis; assess effectiveness of ART and need to switch treatment regimen Reportable range: 20–10,000,000 HIV-1 RNA copies/mL
94016	HIV-1 RNA, Quantitative Real-Time PCR With Reflex to Coreceptor Tropism, UDSa Includes reflex to HIV-1 coreceptor tropism if HIV-1 RNA is ≥1,000 copies/mL.		Evaluate prognosis; assess effectiveness of ART and need to switch treatment regimen. See Table 4 for clinical use of tropism assays.
91691	HIV-1 RNA, Quantitative, Real-Time PCR With Reflex to Genotype (RTI, PI, Integrase)a Includes reflex to HIV-1 Genotype and HIV-1 Integrase Genotype if HIV-1 RNA is >400 copies/mL.		Evaluate prognosis; assess effectiveness of ART and need to switch treatment regimen. See Table 4 for clinical use of genotypic assays.
90926	HIV-1 RNA, Quantitative, Real-Time PCR, With Reflex to Integrase Genotypea Includes reflex to HIV-1 Integrase Genotype if HIV-1 RNA is >400 copies/mL.

ART, antiretroviral therapy; PI, protease inhibitors; RTI, reverse transcriptase inhibitors; UDS, ultradeep sequencing.
a	Reflex tests are performed at an additional charge and are associated with an additional CPT code(s).

 

Antiretroviral drug selection

HIV-1 drug–resistance testing

The development of drug-resistant HIV-1 variants is an important cause of virologic failure (ie, persistent viremia in the presence of drug treatment). Resistance assays are useful for selecting drug regimens when initiating ART or changing regimens because of virologic failure or suboptimal reduction in viral load. HIV drug resistance can be evaluated with genotypic or phenotypic testing. Regardless of the approach, resistance testing should be performed on specimens obtained while the patient is still receiving a failing non–long-acting ART regimen or soon (<4 weeks) after discontinuation; otherwise, resistant variants may not be detected but may re-emerge if the drug is reinstated.4,7 Patients receiving a failing long-acting ART regimen should receive resistance testing regardless of the duration of time after discontinuation.4 Therapy decisions should take into account the results of previous resistance testing.4

HIV-1 genotype

Genotypic HIV resistance assays identify drug resistance-associated mutations in viral nucleic acid sequences obtained from HIV-infected individuals. Relative to phenotypic testing, genotypic testing has the advantages of faster turnaround time, lower cost, and enhanced detection of resistance-associated mutations in mixed virus populations.4 Drug-resistant HIV-1 variants can be transmitted and may affect response to the initial drug regimen. Consequently, genotypic testing is recommended upon entry into care. If therapy is not begun soon thereafter, testing may be repeated before treatment initiation to guide selection of the starting regimen.4,7 Genotypic testing is also generally recommended after the first or second treatment failure.4,7

Quest offers HIV-1 genotyping assays that identify mutations that may confer resistance to protease inhibitors, reverse transcriptase inhibitors, and/or integrase inhibitors (Table 4). Quest employs a rules-based algorithm to interpret the results of this mutation analysis. Thus, predicted drug-resistance patterns are reported in addition to the actual mutations detected. The absence of resistance-associated mutations does not necessarily imply drug susceptibility; mutations in minor viral populations may not be detected but may become predominant in the future.

Standard genotypic testing generally requires a plasma viral load of at least 500 to 1,000 HIV-1 RNA copies/mL.4 For patients with low viral loads or for whom conventional genotypic testing is unsuccessful, testing can be performed on proviral HIV-1 DNA (using a new, separate whole blood specimen) rather than HIV-1 RNA, though results should be interpreted with caution since these assays may not detect all the previous resistance mutations.4

Phenotypic testing

Phenotypic resistance tests assess the ability of HIV to replicate in the presence of selected antiretroviral drugs.4 These assays use a recombinant HIV-1 virus that includes a cloned insert from the patient’s virus. For each selected drug, the assay compares the concentration that inhibits recombinant viral replication by 50% (IC50) with the IC50 of a reference HIV strain. This comparison determines whether the patient’s virus remains susceptible to that drug. Because phenotypic testing reflects the net effect of HIV mutations, it may be particularly useful in highly treatment-experienced patients.4

The addition of phenotypic analysis to genotypic testing is recommended for treatment-experienced patients with known or suspected complex HIV drug–resistance mutation patterns.4 Given the complexity involved in managing treatment-experienced patients, expert advice is recommended when assessing options for those developing virologic failure.4

Table 5 summarizes some of the key differentiating features of genotypic and phenotypic testing.

HIV-1 coreceptor tropism testing

HIV-1 coreceptor tropism testing helps determine eligibility for treatment with CCR5 antagonists. HIV-1 utilizes the CD4 cell surface receptor and 1 of 2 chemokine receptors, CCR5 and/or CXCR4, to infect cells.4 CCR5 antagonists inhibit HIV-1 by binding to CCR5 and are only effective against R5-tropic viruses, which exclusively utilize the CCR5 coreceptor. They do not effectively inhibit either X4-tropic viruses, which exclusively utilize the CXCR4 coreceptor, or dual/mixed (D/M)-tropic viruses, which can utilize both CXCR4 and CCR5. Tropism testing should be performed before initiating a CCR5 antagonist to exclude patients with X4 or D/M tropic virus; testing is also recommended for patients with treatment failure on a CCR5 antagonist.4,7

Although guidelines consider phenotyping to be the preferred method for tropism testing because of its high sensitivity, genotypic tropism testing is a guideline-approved alternative because of its lower cost and faster analytical times.4 The Quest genotypic tropism test is comparable to a high-sensitivity phenotypic test in distinguishing between virologic responders and nonresponders.12 It utilizes next-generation DNA sequencing (ultradeep sequencing) to detect HIV-1 envelope V3 variants associated with X4 and R5 utilization.

Similar to genotypic testing for resistance-associated mutations, standard genotypic tropism testing using blood plasma requires a viral load of at least 1,000 HIV-1 RNA copies/mL. Patients with lower viral loads can be tested with a proviral HIV-1 DNA tropism assay using a whole blood specimen rather than an HIV-1 RNA-based assay using plasma.4

HLA-B*5701 typing

The nucleoside reverse transcriptase inhibitor abacavir is associated with an 8% risk of a hypersensitivity reaction.13 Susceptibility to this serious and sometimes fatal reaction has been associated with a specific human genetic variation known as HLA-B*5701. Patients should receive pharmacogenetic screening for HLA-B*5701 before initiating or reinitiating therapy with abacavir.4,7,13 A negative result indicates that the patient is unlikely to have a hypersensitivity reaction to abacavir but does not rule out this possibility. A positive result indicates that alternatives to abacavir should be used for treatment because abacavir is contraindicated in HLA-B*5701-positive patients.13 This test uses PCR amplification followed by hybridization with sequence-specific oligonucleotide probes to detect the HLA-B*5701 allele.

Table 4. Laboratory Tests Used for Selection of Antiretroviral Drugs

Test code	Test name	Primary clinical use and/or differentiating factors
91299	HIV-1 Coreceptor Tropism, Proviral DNAa	Evaluate eligibility for therapy with CCR5 antagonist (genotypic assay) in patients with low plasma viral load (<1,000 HIV-1 RNA copies/mL)
94014	HIV-1 Coreceptor Tropism, Ultradeep Sequencinga	Evaluate eligibility for therapy with CCR5 antagonist (genotypic assay)
34949	HIV-1 Genotypea	Detect mutations associated with resistance to RTI and PI
91692	HIV-1 Genotype (RTI, PI, Integrase Inhibitors)a Includes HIV-1 Genotype and HIV-1 Integrase Genotype.	Detect mutations associated with resistance to RTIs, PIs, and integrase inhibitors
94015	HIV-1 Genotype and Coreceptor Tropism, Ultradeep Sequencinga	Detect mutations associated with resistance to RTI and PI; evaluate eligibility for therapy with CCR5 antagonist
16868	HIV-1 Integrase Genotypea	Detect mutations associated with resistance to integrase inhibitors (raltegravir, elvitegravir, dolutegravir, bictegravir, and cabotegravir)
94810	HIV-1 Resistance and Coreceptor Tropism, Proviral DNAa	Detect mutations associated with resistance to RTIs, PIs, and integrase inhibitors; evaluate eligibility for therapy with CCR5 antagonist in patients with low plasma viral load (<1,000 HIV-1 RNA copies/mL)
94809	HIV-1 Resistance, Proviral DNA (Integrase Inhibitors)a	Detect mutations associated with resistance to integrase inhibitors in patients with low plasma viral load (<1,000 HIV-1 RNA copies/mL)
94808	HIV-1 Resistance, Proviral DNA (RT, PI Inhibitors)a	Detect mutations associated with resistance to RTIs and PIs in patients with low plasma viral load (<1,000 HIV-1 RNA copies/mL)
94807	HIV-1 Resistance, Proviral DNA (RTI, PI, Integrase Inhibitors)a	Detect mutations associated with resistance to RTIs, PIs, and integrase inhibitors in patients with low plasma viral load (<1,000 HIV-1 RNA copies/mL)
19774	HLA-B*5701 Typingb	Assess risk of abacavir hypersensitivity reaction

PI, protease inhibitors; RTI, reverse transcriptase inhibitors.
a	This test was developed and its analytical performance characteristics have been determined by Quest. It has not been cleared or approved by the US Food and Drug Administration. This assay has been validated pursuant to the CLIA regulations and is used for clinical purposes.
b	Typing performed by using allele-specific polymerase chain reaction (AS-PCR) with reflex to the FDA-cleared LABType® SSO Kit. The AS-PCR portion of the test was developed and its performance characteristics have been determined by Quest.

 

Table 5. Differentiating Features of Genotypic and Phenotypic HIV Resistance Testing

Genotype4	Phenotype4
Relatively rapid turnaround time (1-2 weeks) Lower cost Greater sensitivity than phenotype for the detection of resistance-associated mutations in mixed virus populations Qualitative assessment of resistance (resistance likely or not likely) Useful in most clinical settings that call for resistance testing	Longer turnaround time (2-3 weeks) Higher cost Direct in vitro measurement of drug susceptibility of patient virus population Presents sum effect of mutations on susceptibility to each drug (fold-change value) Useful in patients with complex mutation patterns

 

Monitoring patient health

Blood count, basic chemistry, glucose, and lipid testing

Both HIV infection and the drugs used to treat it can occasionally have adverse effects on various organ systems. Moreover, because patients with HIV infection now tend to live longer lifespans, more emphasis is being given to routine screening. Periodic monitoring of patient health after entry into care typically includes complete blood count, basic chemistry tests, markers of liver and kidney function and bone health, and evaluation of glucose and lipid profile (Figure). Please see current guidelines for comprehensive monitoring recommendations4,7 and refer to the Quest online Test Directory for testing options.

Testing for comorbid conditions

Table 6 describes tests used to screen for comorbid conditions in individuals with HIV infection. Current guidelines recommend testing for several comorbid infectious diseases, including tuberculosis, viral hepatitis (A, B, and C), measles, trichomoniasis, varicella zoster virus, chlamydia, gonorrhea, and syphilis.7 Additional testing, including glucose-6-phosphate dehydrogenase, testosterone, and cervical and/or anal cancer screening, is recommended for those with appropriate clinical indications.7

Table 6. Laboratory Tests Used to Screen for Comorbid Conditions in Individuals With HIV-1 Infection Entering Carea

Test code	Test name		Primary clinical use
Cancer screening (cervical and anal)
10676	Cytology, Non-Gynecological, Fluid, Washings, Brushings or FNA		Detect abnormal anal cytology
18810	SurePath™ Imaging Papb		Detect abnormal cervical cytology
14471	SurePath™ Papb
15095	SurePath™ Pap and HPV mRNA E6/E7b		Detect abnormal cervical cytology; detect the presence of high-risk HPV types
58315	ThinPrep® Imaging System Papb		Detect abnormal cervical cytology
35455	ThinPrep® Papb
90931	ThinPrep® Pap and HPV mRNA E6/E7b		Detect abnormal cervical cytology; detect the presence of high-risk HPV types
Chlamydia, gonorrhea, and trichomoniasis
16505	Chlamydia trachomatis RNA, TMA, Rectalc	Detect infection with C trachomatis
70048	Chlamydia trachomatis RNA, TMA, Throatc
11361	Chlamydia trachomatis RNA, TMA, Urogenital
16492	Chlamydia/N gonorrhoeae and T vaginalis RNA, Qualitative, TMA Includes Chlamydia/Neisseria gonorrhoeae RNA, TMA, Urogenital and Trichomonas vaginalis RNA, Qualitative, TMA.	Detect infection with C trachomatis, N gonorrhoeae, or T vaginalis
91448	Chlamydia/N gonorrhoeae and T vaginalis RNA, Qualitative, TMA, Pap Vialc Includes Chlamydia/Neisseria gonorrhoeae RNA, TMA, Urogenital and Trichomonas vaginalis RNA, Qualitative, TMA, Pap Vial.
16506	Chlamydia/Neisseria gonorrhoeae RNA, TMA, Rectalc	Detect infection with C trachomatis or N gonorrhoeae
70051	Chlamydia/Neisseria gonorrhoeae RNA, TMA, Throatc
11363	Chlamydia/Neisseria gonorrhoeae RNA, TMA, Urogenital
16504	Neisseria gonorrhoeae RNA, TMA, Rectalc	Detect infection with N gonorrhoeae
70049	Neisseria gonorrhoeae RNA, TMA, Throatc
11362	Neisseria gonorrhoeae RNA, TMA, Urogenital
19550	Trichomonas vaginalis RNA, Qualitative, TMA	Detect infection with T vaginalis
90521	Trichomonas vaginalis RNA, Qualitative, TMA, Pap Vialc
G6PD deficiency
500	Glucose-6-Phosphate Dehydrogenase, Quantitative		Assess G6PD enzyme level
Hypogonadism
15983	Testosterone, Total, MSd		Assess total testosterone level
Measles
964	Measles Antibody (IgG), Immune Status		Assess for immunity against measles
5259	Measles, Mumps, and Rubella (MMR) Antibodies (IgG) Panel, Immune Status Includes measles antibody (IgG), mumps virus antibody (IgG), and rubella antibody (IgG).		Assess for immunity against measles, mumps, and rubella
Syphilis
36126	RPR (Diagnosis) With Reflex to Titer and Confirmatory Testinge Includes RPR screen with reflex to titer and fluorescent treponemal antibody.	Detect non-treponemal (reagin) antibodies associated with syphilis
90349	Syphilis Antibody Cascading Reflexe Includes Treponema pallidum antibody immunoassay and reflex to RPR screen, which reflexes to either RPR titer or T pallidum antibody particle agglutination assay.	Detect and confirm presence of antibody to T pallidum
653	Treponema pallidum Antibody, Particle Agglutination	Confirm presence of antibody to T pallidum
Tuberculosis
36970	QuantiFERON®-TB Gold Plus, 1 Tube		Detect infection with M tuberculosis
36971	QuantiFERON®-TB Gold Plus, 4 Tubes, Draw Site Incubated
37737	T-SPOT®.TB
Varicella zoster virus
4439	Varicella-Zoster Virus Antibody (IgG)	Assess for immunity against varicella-zoster virus due to previous infection
14505	Varicella-Zoster Virus Antibody (Immunity Screen), ACIFd	Assess for immunity against varicella-zoster virus due to previous infection or vaccination
Viral hepatitis
508	Hepatitis A Antibody, Total	Indicates prior or acute infection with, or immunization to, hepatitis A virus
498	Hepatitis B Surface Antigen With Reflex Confirmatione	First-line diagnostic test for acute hepatitis B; indicates chronic hepatitis when still positive 6 months after diagnosis of acute HBV infection
556	Hepatitis Be Antibody	Indicator of resolution or carrier state when interpreted along with the other hepatitis B markers
555	Hepatitis Be Antigen	Indicator of active viral replication and high infectivity
94345	Hepatitis C Antibody With Reflex to HCV RNA, PCR With Reflex to Genotype, LiPAe Includes hepatitis C antibody immunoassay with reflex to HCV RNA; if HCV RNA ≥300 IU/mL, then reflex to HCV genotype.	Screen for and confirm presence of HCV infection; establish viral load at baseline; determine HCV genotype and subtype
8472	Hepatitis C Antibody With Reflex to HCV, RNA, Quantitative, Real-Time PCRe	Screen for and confirm presence of HCV infection; establish viral load at baseline
35645	Hepatitis C Viral RNA, Quantitative, Real-Time PCRc	Confirm HCV infection; establish viral load at baseline; determine duration of treatment

ACIF, anti-complement immunofluorescence; FNA, fine needle aspiration; G6PD, glucose-6-phosphate dehydrogenase; HBV, hepatitis B virus; HCV, hepatitis C virus; HPV, human papillomavirus; MS, mass spectrometry; RPR, rapid plasma reagin; TB, tuberculosis; TMA, transcription-mediated amplification.
a	This test listing is based on guidelines from the HIV Medicine Association of the Infectious Diseases Society of America.7 It is not intended to be comprehensive. For additional testing options, consult the Quest online Test Directory (TestDirectory.QuestDiagnostics.com). Components of panels and reflex tests may be ordered individually.
b	Pap results requiring physician interpretation will be performed at an additional charge and associated with an additional CPT code(s).
c	The analytical performance characteristics of this assay have been determined by Quest. The modifications have not been cleared or approved by the FDA. This assay has been validated pursuant to the CLIA regulations and is used for clinical purposes.
d	This test was developed and its analytical performance characteristics have been determined by Quest. It has not been cleared or approved by the FDA. This assay has been validated pursuant to the CLIA regulations and is used for clinical purposes.
e	Reflex tests are performed at an additional charge and are associated with an additional CPT code(s).