For an ART‑naïve adult, when will the baseline quantitative HIV‑RNA viral load we sent to the laboratory be reported, and how should the result guide counseling, resistance testing, and subsequent viral‑load monitoring?

Baseline HIV Viral Load Testing and Clinical Management

For an ART-naïve adult, the baseline quantitative HIV-RNA viral load result will typically be available within days to 1-2 weeks depending on your laboratory, and you should not delay ART initiation while waiting for this result. 1

Timing of Viral Load Results and ART Initiation

• Start ART immediately after obtaining the baseline viral load specimen, without waiting for results, unless there is preexisting severe kidney or liver damage or high likelihood of transmitted drug resistance. 1
• The baseline viral load should be drawn at the time of HIV diagnosis to characterize HIV stage and establish a reference point for monitoring treatment response. 1
• For patients with advanced HIV disease (CD4 <100/μL), initiate ART after the first viral load measurement is obtained to prevent potentially deleterious treatment delays. 1

Baseline Resistance Testing Requirements

Order a baseline reverse transcriptase–protease inhibitor genotype resistance test before initiating ART to detect transmitted NRTI, NNRTI, and PI resistance. 1, 2

• Baseline integrase (InSTI) genotyping is not recommended unless there is known exposure to a partner with InSTI resistance. 1
• High rates of transmitted drug resistance make baseline genotyping essential for selecting an effective initial regimen. 1, 2
• Do not delay ART initiation while waiting for genotype results—start treatment and adjust the regimen later if resistance is detected. 1

Counseling Based on Baseline Viral Load

Counsel the patient that the baseline viral load indicates their current level of viral replication and helps predict time to viral suppression, but emphasize that adherence to ART is far more important than the starting viral load. 1

• Higher baseline viral loads (>100,000 copies/mL) may take longer to achieve undetectable levels but do not preclude excellent treatment outcomes with adherence. 1
• Patients should expect a substantial decrease (≥1.0 log₁₀ or 10-fold reduction) in viral load by 2-8 weeks after starting ART. 1
• With modern integrase inhibitor-based regimens and good adherence, most patients achieve viral suppression (<50 copies/mL) by 16-24 weeks. 1

Subsequent Viral Load Monitoring Schedule

Measure the first on-treatment viral load at 4-6 weeks after ART initiation to assess initial treatment effectiveness. 1

• If the viral load has not declined substantially (≥1.0 log₁₀) by 4-6 weeks and adherence appears sufficient, obtain genotypic resistance testing according to the patient's regimen. 1
• Continue monitoring viral load every 3 months until the patient achieves viral suppression (<50 copies/mL) for at least 1 year. 1
• After 1 year of consistent viral suppression with maintained adherence, reduce monitoring frequency to every 6 months. 1

Additional Baseline Laboratory Testing

Before starting ART, obtain the following tests (but do not delay treatment for results): 1

• CD4 cell count to characterize HIV stage and determine need for opportunistic infection prophylaxis
• Serum cryptococcal antigen if CD4 <100/μL, even without symptoms
• Kidney function (creatinine, eGFR), liver function (AST, ALT, bilirubin), complete blood count, lipid panel, blood glucose, and pregnancy test if applicable
• Hepatitis A, B, and C serologies; tuberculosis screening; sexually transmitted infection screening

Common Pitfalls to Avoid

• Do not measure viral load during or within 4 weeks after intercurrent infections, vaccinations, or symptomatic illness, as these can cause transient elevations unrelated to treatment failure. 1, 3
• Use the same laboratory and same assay method for all serial viral load measurements to ensure consistent results and avoid variability between testing platforms. 1, 3
• Do not obtain a second baseline viral load to "confirm" the result before starting ART—this only delays treatment without clinical benefit in most patients. 1
• Recognize that HIV RNA assays have inherent variability of approximately 0.5 log₁₀ (threefold) in either direction, which is greater at very low levels. 3