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Lab Manual for UCSF Clinical Laboratories

Lab Manual for SFGH

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Item Value
Available Stat? No
Test code HIVL
Performed by? Microbiology (Serology)
Sendout? no
Price range $$$
In House Availability 2 - 7 day TAT
Principle HIV-1 viral nucleic acid is measured by a Real Time PCR assay.

This assay uses RT-PCR to generate amplified product from the RNA genome of HIV-1 in clinical specimens. An RNA sequence that is unrelated to the HIV-1 target sequence is introduced into each specimen at the beginning of sample preparation. This unrelated RNA sequence is simultaneously amplified by RT-PCR, and serves as an internal control (IC) to demonstrate that the process has proceeded correctly for each sample. The amount of HIV-1 target sequence that is present at each amplification cycle is measured through the use of fluorescent-labeled oligonucleotide probes. The probes do not generate a signal unless they are specifically bound to the amplified product. The amplification cycle at which fluorescent signal is detected is proportional to the log of the HIV-1 RNA concentration present in the original sample.

Results range from less than 40 copies to greater than 10,000,000 copies/mL plasma.
Interpretation Viral Load is used to monitor HIV-1 levels in patients on multidrug antiretroviral therapy and to assess therapeutic efficacy.

This test is not intended to establish the diagnosis of HIV-1 infection and should be ordered only for patients with previously documented HIV-1 infection. Confusing false-positive low viral load results may occur in uninfected patients. Before anti-retroviral therapy is initiated, a baseline level should be obtained, with two determinations 2-4 weeks apart. The HIV-1 Viral Load test should not be performed within 1 month of acute illness or immunizations (e.g., influenza, tetanus or pneumococcus) because immune activation may affect the test results (1,2).
Container type PPT-EDTA (white/pearl top) tube
Amount to Collect Two (2) dedicated, 5 mL EDTA-PPT tubes
Sample type Blood
Normal range Not Detected
Stability Specimen must be received in Clinical Lab within 4 hours from draw. Plasma is immediately separated and frozen by Clinical Laboratory Staff. Frozen plasma is stable at -70°C for one month.
References 1. Saag, MS, et al., HIV viral load markers in clinical practice, Nature Medicine 2(6): 625-629, 1996.

2. Stanley, SK, et al., Effect of immunization with a common recall antigenon viral expression in patients infected with HIV-1. New Engl. J. Med. 334:1222-30, 1996.
CPT coding 87536
Last Updated 9/12/2012 2:36:03 PM
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