Laboratory Monitoring for Ongoing PrEP Management
For patients on oral PrEP, perform HIV testing quarterly using a laboratory-based antigen/antibody test, with creatinine clearance assessment at 3 months and then annually (more frequently if risk factors present), plus quarterly STI screening and annual hepatitis C testing. 1
HIV Testing Schedule
- Quarterly HIV testing is mandatory using a laboratory-based HIV antigen/antibody combination test 1
- At the 1-month follow-up visit after PrEP initiation, perform a combined HIV antibody and antigen test 1
- If HIV RNA testing was not available at initiation, repeat antigen/antibody testing 1 month after starting or resuming tenofovir-based oral PrEP 1
- For patients on long-acting cabotegravir PrEP, perform a rapid point-of-care HIV test on the day of each injection (every 8 weeks) plus a laboratory-based antigen/antibody test, but routine RNA testing is not recommended 1
Renal Function Monitoring
- Calculate creatinine clearance at the first quarterly follow-up visit (approximately 3 months after initiation) 1
- Subsequently, evaluate creatinine clearance annually for patients without risk factors 1
- For high-risk patients, monitor creatinine clearance every 3-6 months if they are: 1
- Older than 50 years
- Have baseline creatinine clearance below 90 mL/min before PrEP initiation
- Have comorbidities predisposing to kidney dysfunction (diabetes, hypertension)
STI Screening
- Perform quarterly testing for: 1
- N. gonorrhoeae and C. trachomatis using nucleic acid amplification testing (NAAT) at genital and nongenital contact sites
- Syphilis serology
- Adjust testing frequency based on individual risk 1
- Routine testing for Mycoplasma genitalium in asymptomatic individuals is not recommended 1
Hepatitis C Screening
- Test hepatitis C virus antibody annually 1
- Increase frequency to every 3-6 months for: 1
- People who inject drugs
- Men who have sex with men who engage in sex while using drugs
- If clinical suspicion of hepatitis or incidental liver function abnormalities are found, perform a workup for all nonimmune types of viral hepatitis 1
Special Monitoring for Long-Acting Cabotegravir
- Perform STI testing every 4 months (at every second injection) 1
- Administer liver enzyme tests every 6 months 1
- Rapid point-of-care HIV testing should be done on the day of each injection prior to administration 1
Critical Pitfalls to Avoid
Never delay HIV testing beyond the quarterly schedule, as PrEP medications can suppress HIV viral load, delay seroconversion, and decrease the ability to detect HIV infection if breakthrough occurs 1, 2. This makes timely testing essential for early detection.
Do not skip the 1-month follow-up visit after PrEP initiation, as this is crucial for detecting acute HIV infection that may have been present but undetectable at baseline 1.
Always use laboratory-based antigen/antibody tests rather than relying solely on rapid tests for routine monitoring, as they have superior sensitivity for detecting early infection 1.
For patients with recent exposure to long-acting injectable PrEP (cabotegravir) within the past 12 months, include an HIV RNA test in addition to antigen/antibody testing, as injectable agents can particularly mask early infection 1.