What are the recommended lab monitoring intervals for an adult HIV-positive patient or a patient at high risk of HIV acquisition taking Truvada (Emtricitabine/Tenofovir Disoproxil Fumarate) with no significant medical history?

Lab Monitoring for Truvada: Recommended Intervals

For HIV-positive patients on Truvada for treatment, monitor HIV RNA at 4-6 weeks after initiation, then every 3 months until suppressed for at least 1 year, after which monitoring can be reduced to every 6 months if clinically stable and adherent. 1

For HIV-negative patients taking Truvada as PrEP, HIV testing must occur every 3 months without exception, and PrEP prescriptions should never exceed 90 days without interval HIV testing. 1, 2

HIV Treatment Setting (HIV-Positive Patients)

Initial Baseline Testing (Before Starting Truvada)

• HIV RNA level and CD4 count to establish disease stage 1
• Serum creatinine and estimated creatinine clearance (Truvada contraindicated if CrCl <30 mL/min for treatment) 2
• Hepatitis B surface antigen, hepatitis C antibody, and hepatitis A serology 1
• Complete blood count, comprehensive metabolic panel, lipid panel, and blood glucose 1
• Pregnancy test in individuals of childbearing potential 1
• STI screening (gonorrhea, chlamydia, syphilis at all exposed sites) 1
• Urine glucose and urine protein (baseline renal tubular function assessment) 2

Early Treatment Phase Monitoring

• HIV RNA at 4-6 weeks after starting Truvada to assess early virologic response and adherence 1
• HIV RNA every 3 months until viral suppression (<50 copies/mL) is maintained for at least 1 year 1
• CD4 count every 6 months until consistently above 250 cells/μL for at least 1 year with concurrent viral suppression 1

Stable/Maintenance Phase Monitoring

• HIV RNA every 6 months once virologically suppressed and adherent for >1 year 1
• HIV RNA annually is acceptable after >5 years of stable suppression if the patient prefers less frequent monitoring 1
• CD4 counts can be discontinued once consistently >250 cells/μL for ≥1 year with viral suppression, unless virologic failure occurs or immunosuppressive conditions develop 1
• Serum creatinine and estimated creatinine clearance at least annually, with more frequent monitoring (every 3-6 months) in patients >50 years old or with baseline renal risk factors 2
• Urine glucose and urine protein at least annually to monitor for proximal renal tubulopathy 1, 2

Additional Considerations for HIV Treatment

• If HIV RNA rises above 50 copies/mL after previous suppression, repeat HIV RNA in 2-4 weeks and assess adherence 1
• If HIV RNA remains >200 copies/mL on two consecutive measurements, obtain genotype resistance testing while still on the failing regimen 1
• Monitor for bone pain, fractures, or muscle weakness as these may indicate proximal renal tubulopathy requiring immediate renal function evaluation 2

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HIV PrEP Setting (HIV-Negative Patients)

Pre-Initiation Testing (Within 7 Days Before Starting)

• Combined HIV antibody-antigen assay (4th or 5th generation) is mandatory to exclude HIV infection 1, 2
• HIV RNA testing should ideally be added if acute HIV infection is suspected or in high-risk populations 1
• Serum creatinine and estimated creatinine clearance (Truvada contraindicated for PrEP if CrCl <60 mL/min) 1, 2
• Hepatitis B surface antigen (critical because stopping tenofovir in HBV-positive patients risks hepatitis flares) 1, 2
• Hepatitis C antibody 1
• STI screening (gonorrhea, chlamydia by NAAT at all exposed sites including urine, throat, rectal, and vaginal) 1
• Syphilis serology 1
• Pregnancy test in individuals of childbearing potential 1

Early PrEP Phase Monitoring

• 1-month follow-up visit to assess adherence, tolerability, and repeat HIV testing to exclude primary HIV infection that may have been in the window period 1
• HIV testing every 3 months using combined antibody-antigen assay (this is non-negotiable) 1, 2
• PrEP prescriptions must not exceed 90 days without interval HIV testing 1, 2

Ongoing PrEP Monitoring (Every 3 Months)

• HIV antibody-antigen testing at every visit 1, 2
• STI screening (gonorrhea, chlamydia, syphilis at all exposed mucosal sites) 1
• Serum creatinine and estimated creatinine clearance 1, 2
• Urine glucose and urine protein 2
• Pregnancy testing every 3 months in individuals of childbearing potential 1
• Hepatitis C serology at least annually, more frequently in people who inject drugs or those with elevated transaminases 1

Critical PrEP Safety Monitoring

• If creatinine clearance decreases during PrEP, evaluate potential causes and reassess risks/benefits of continuation 2
• Avoid concurrent nephrotoxic agents (especially high-dose or multiple NSAIDs) as acute renal failure has been reported when combined with tenofovir 2
• Monitor for proximal renal tubulopathy signs: persistent bone pain, fractures, muscle weakness, hypophosphatemia, or euglycemic glycosuria 2
• Patients with chronic kidney disease should also have serum phosphorus monitored 2

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Common Pitfalls to Avoid

• Never extend PrEP prescriptions beyond 90 days without HIV testing – this is an FDA-mandated safety requirement to prevent undiagnosed HIV infection leading to functional monotherapy and resistance 1, 2
• Do not use Truvada for PrEP if CrCl <60 mL/min – switch to TAF/FTC instead for patients with CrCl 30-59 mL/min 1, 2
• Do not use Truvada for treatment if CrCl <30 mL/min or in patients requiring hemodialysis 2
• Never stop monitoring renal function – glomerular dysfunction can occur particularly in patients >50 years and is usually reversible if caught early 1, 2
• In patients with hepatitis B co-infection, stopping tenofovir can cause severe hepatitis flares and hepatic decompensation, so ensure HBsAg testing before initiation 2
• For HIV treatment patients, do not continue CD4 monitoring indefinitely – it can be safely discontinued once >250 cells/μL for ≥1 year with viral suppression 1