What baseline laboratory tests and initial antiretroviral therapy should be ordered for a patient with known HIV infection?

Baseline Laboratory Testing and Initial Antiretroviral Therapy for HIV-Positive Patients

For a patient with newly diagnosed HIV infection, immediately order the following baseline tests and start antiretroviral therapy (ART) as soon as possible, ideally at the first visit, without waiting for all results to return. 1

Essential Baseline Laboratory Tests

Confirm Diagnosis and Assess Disease Status

• HIV-1 RNA level (viral load) - quantifies virus and establishes baseline 1
• CD4+ T cell count - determines immune status and disease stage 1
• HIV genotype testing for reverse transcriptase and protease resistance mutations - guides initial regimen selection 1
• Do NOT routinely test for integrase resistance at baseline unless the patient previously used cabotegravir-containing PrEP or acquired HIV from a partner with known integrase-resistant virus 1

Screen for Co-infections

• Hepatitis B surface antigen (HBsAg) - identifies active hepatitis B requiring specific treatment considerations 1
• Hepatitis C antibody (IgG) - screens for hepatitis C; if positive, confirm with HCV RNA 1
• Hepatitis A IgG antibody - determines need for vaccination 1
• Latent tuberculosis testing - screens for TB requiring treatment before or with ART 1
• Sexually transmitted infection (STI) screening - test for gonorrhea, chlamydia, and syphilis at all exposed sites 1
• If CD4 count <100 cells/μL: cryptococcal antigen testing - identifies life-threatening infection requiring immediate treatment 1

Assess General Health and Organ Function

• Serum creatinine and estimated glomerular filtration rate (eGFR) - evaluates kidney function before starting tenofovir-containing regimens 1
• Complete blood count (CBC) - identifies cytopenias 1
• Liver function tests (AST, ALT, bilirubin) - assesses hepatic function 1
• Fasting lipid panel and glucose - establishes cardiovascular risk baseline 1
• Pregnancy test for individuals of childbearing potential 1

Special Testing Before Specific Medications

• HLA-B*5701 testing - MUST be negative before using abacavir to prevent potentially fatal hypersensitivity reaction 1
• Urine glucose and protein - baseline if starting tenofovir disoproxil fumarate (TDF) 1

Recommended Initial Antiretroviral Therapy Regimens

Start one of these preferred regimens immediately after diagnosis, even before all test results return (except HLA-B*5701 if considering abacavir): 1

First-Line Preferred Regimens (Listed Alphabetically)

1. Bictegravir/tenofovir alafenamide (TAF)/emtricitabine (FTC) - single tablet, once daily 1
2. Dolutegravir + TAF/FTC - once daily 1
3. Dolutegravir/abacavir/lamivudine - single tablet, once daily (only if HLA-B*5701 negative) 1

These integrase inhibitor-based regimens are preferred because they have high efficacy, low pill burden, minimal drug interactions, can be taken with or without food, and have a high barrier to resistance. 1 Bictegravir and dolutegravir do not require pharmacologic boosting, reducing drug interaction concerns. 1

Alternative Regimens (When Preferred Options Unavailable)

• Darunavir/cobicistat + TAF (or TDF)/FTC 1
• Darunavir/ritonavir + TAF (or TDF)/FTC 1
• Raltegravir + TAF (or TDF)/FTC 1

Important Medication Selection Considerations

• Avoid NNRTIs (efavirenz, rilpivirine) for rapid ART start due to higher resistance risk and need for resistance testing results 1
• Do NOT use TDF in patients with or at risk for kidney or bone disease - use TAF instead 1
• Do NOT use abacavir without confirmed negative HLA-B*5701 testing 1
• For patients with active hepatitis B, ensure regimen includes agents active against HBV (tenofovir + emtricitabine or lamivudine) 1

Critical Timing Principles

Start ART immediately upon diagnosis, including same-day initiation if the patient is ready to commit to treatment. 1 The evidence strongly supports rapid initiation to reduce morbidity and mortality. 1

Do not delay treatment waiting for resistance testing results - start with a preferred integrase-based regimen and adjust later if needed based on genotype. 1 The only exception is waiting for HLA-B*5701 results if planning to use abacavir. 1

Early Monitoring After Starting ART

• At 4-6 weeks: measure HIV RNA level to confirm treatment response (should see >0.5-0.75 log10 decline) 1
• At 12-24 weeks: HIV RNA should be <200 copies/mL (ideally undetectable <50 copies/mL) 1
• If viral load has not declined appropriately, assess adherence immediately and consider resistance testing while patient remains on the failing regimen 1
• Once suppressed (<50 copies/mL), monitor HIV RNA every 3 months for the first year, then every 6 months if consistently suppressed with good adherence 1
• Monitor CD4 count every 6 months until >250 cells/μL for at least 1 year with viral suppression 1

Common Pitfalls to Avoid

Do not add a single active agent to a failing regimen - this promotes resistance. 1 Always use at least two fully active agents when changing therapy for virologic failure. 1

Do not use two-drug initial regimens outside of clinical trials or very specific circumstances where patients cannot tolerate standard three-drug regimens. 1

Do not delay ART for opportunistic infection prophylaxis - start ART within 2 weeks for most opportunistic infections, and primary MAC prophylaxis is no longer needed if effective ART is started. 1