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HelpTest ID HIVQG HIV-1 RNA Quantification with Reflex to HIV-1 Genotypic Drug Resistance, Plasma
Useful For
Detecting and quantifying plasma HIV-1 RNA levels (viral load) in HIV-1-infected patients, followed by genotypic determination of viral resistance to anti-HIV drugs
Guiding initiation or change of antiretroviral treatment regimens
Reflex Tests
| Test ID | Reporting Name | Available Separately | Always Performed |
|---|---|---|---|
| HIVPR | HIV-1 Genotypic PR-RT Resistance, P | Yes | No |
Testing Algorithm
If HIV-1 RNA titer is ≥500 copies/mL, then HIV-1 genotypic drug resistance mutations will be determined at an additional charge.
See HIV Treatment Monitoring Algorithm in Special Instructions.
Special Instructions
Method Name
Real Time Reverse Transcription-Polymerase Chain Reaction (RT-PCR)
Reporting Name
HIV-1 RNA reflex to Genotyp Resist, PSpecimen Type
Plasma EDTACollection Container/Tube: Lavender top (EDTA)
Submission Container/Tube: Plastic vial
Specimen Volume: 3 mL
Collection Instructions:
1. Spin down and remove plasma from cells within 6 hours of draw.
2. Freeze plasma specimen immediately, and ship specimen frozen on dry ice.
3. If shipment will be delayed for >24 hours, freeze plasma specimen at -70° C (up to 35 days) until shipment on dry ice.
Additional Information: This test can be used for detection and diagnosis of HIV-1 infections, including in children <18 months of age when serologic tests are not useful (due to presence of maternal HIV antibodies).
Specimen Minimum Volume
2 mL
Specimen Stability Information
| Specimen Type | Temperature | Time |
|---|---|---|
| Plasma EDTA | Frozen (preferred) | 35 days |
| Refrigerated | 5 days |
Clinical Information
HIV-1 is an RNA virus that infects human host cells and is then converted to complementary DNA (cDNA) by the action of viral reverse transcriptase. HIV-1 is the causative agent of AIDS, a severe, life-threatening condition.
Currently, 2 types of HIV, HIV type 1 (HIV-1) and HIV type 2 (HIV-2), are known to infect humans. HIV-1 has been isolated from patients with AIDS, AIDS-related complex, and asymptomatic infected individuals at high-risk for AIDS. Accounting for >99% of HIV infection in the world, HIV-1 is transmitted by sexual contact, by exposure to infected blood or blood products, from an infected pregnant woman to fetus in utero or during birth, or from an infected mother to infant via breast feeding. HIV-2 has been isolated from infected patients in West Africa and it appears to be endemic only in that region. However, HIV-2 also has been identified in individuals who have lived in West Africa or had sexual relations with individuals from that geographic region. HIV-2 is similar to HIV-1 in its morphology, overall genomic structure, and ability to cause AIDS.
Multiple clinical studies of plasma HIV-1 viral load (expressed as HIV-1 RNA copies/mL of plasma) have shown a clear relationship of HIV-1 RNA copy number to stage of HIV-1 disease and efficacy of anti-HIV-1 therapy. Quantitative HIV-1 RNA level in plasma (ie, HIV-1 viral load) is an important surrogate marker in assessing the risk of disease progression and monitoring response to anti-HIV-1 drug therapy in the routine medical care of HIV-1-infected patients.
Studies have identified a number of mutations associated with antiviral resistance. Genotypic analysis allows identification of nucleotide changes associated with HIV drug resistance. When combination therapy fails, genotyping for drug resistance mutations may help direct appropriate changes in antiretroviral therapy and may result in at least a short-term benefit, as evidenced by viral load reduction.
Reference Values
Undetected
Cautions
The HIV-1 RNA detection and quantification assay is not licensed by the FDA as a screening test for HIV-1 infection in donors of blood, human cells, tissues, or tissue products.
Although this quantitative HIV-1 RNA test is not FDA approved for diagnostic purposes, the United States Working Group on Antiretroviral Therapy and Medical Management of HIV-Infected Children recommends the use of molecular-based assays to detect HIV-1 RNA or proviral DNA for the diagnosis of HIV infection in infants of <18 months of age and born to HIV-infected mothers.
A single HIV-1 viral load test result should not be used as the sole criterion in guiding therapeutic decisions and intervention in the clinical care of HIV-1-infected patients. Viral load results should be correlated with patient symptoms, clinical presentation, and CD4 cell count. Due to the inherent variability in the assay, physiologic variation and concurrent illnesses in the infected patients, <100-fold (<2 log) changes in plasma HIV-1 viral load should not be considered to be significant changes.
Viral load results of <20 copies/mL do not necessarily indicate absence of HIV-1 viral replication. Inhibitory substances may be present in the plasma specimen, leading to negative or falsely low HIV-1 RNA results. Improper specimen collection or storage may lead to negative or falsely lower plasma viral load results.
Although this commercial HIV-1 viral load assay is optimized for quantification of plasma viral load in HIV-1 infection due to HIV-1 groups M (subtypes A to H) and O strains, results generated from HIV-1 group O strains may be discordant (≥0.5 log copies/mL) with those obtained from other commercially available HIV-1 viral load assays. The assay is not reliable for quantifying plasma viral loads in infection caused by HIV-1 group N and HIV-2 strains.
ACD plasma specimens are not optimal for HIV-1 viral load testing because such plasma specimens show HIV-1 RNA levels that are approximately 15% lower than those collected in tubes containing EDTA.
Day(s) Performed
HIV-1 quantification: Monday through Saturday; 7 a.m.-4 p.m.
HIV-1 genotyping: varies; test will be performed in batches of 10 specimens
Report Available
Monday through Thursday, 1 day; Friday and Saturday, 3 daysPerforming Laboratory
Mayo Medical Laboratories in Rochester
Test Classification
This test has been modified from the manufacturer's instructions. Its performance characteristics were determined by Mayo Clinic in a manner consistent with CLIA requirements. This test has not been cleared or approved by the U.S. Food and Drug Administration.CPT Code Information
87536-HIV-1, quantification
87901-HIV-1 genotypic drug resistance (if appropriate)