From the Guidelines
Standard laboratory tests for maintaining PrEP treatment in the USA include HIV testing every 3 months, kidney function tests (creatinine clearance) at least every 6 months, STI screening every 3-6 months, and pregnancy testing for people who can become pregnant. These tests are crucial for monitoring the effectiveness of PrEP treatment and preventing potential complications. According to the 2020 recommendations of the International Antiviral Society-USA panel 1, the following laboratory tests are recommended for individuals on PrEP:
- Combined HIV antibody and antigen test at 1 month, quarterly, and annually
- Estimated creatinine clearance rate at the first quarterly visit and annually thereafter, or every 3 to 6 months for patients with or at risk for kidney injury
- Genital and nongenital gonorrhea and chlamydia testing by NAAT quarterly
- Syphilis testing quarterly
- Pregnancy testing for individuals of childbearing potential quarterly
- Hepatitis C virus antibody test annually, or every 3-6 months for people who inject drugs or MSM who use recreational drugs at the time of sex if liver function test results are abnormal
Regular monitoring of these laboratory tests is essential to ensure the safe and effective use of PrEP treatment. Healthcare providers may adjust the monitoring schedule based on individual patient factors and risk profiles 1. It is also important to note that PrEP should not be initiated until HIV RNA test results confirm uninfected status for HIV in the setting of clinical suspicion or clinical signs or symptoms consistent with acute or primary HIV infection 1.
From the Research
Standard Laboratory Tests for Maintaining Pre-Exposure Prophylaxis (PrEP) Treatment in the USA
The standard laboratory tests for maintaining PrEP treatment in the USA include:
- HIV testing 2
- Syphilis testing 2
- Chlamydia and gonorrhea testing 2
- Hepatitis B testing 2
- Creatinine level measurement to assess kidney function 3, 4, 5, 2
- Urine dipstick for protein to assess kidney function 3
- Estimated glomerular filtration rate (eGFR) calculation using serum creatinine and/or cystatin C 3, 4
- Urine biomarker panel to assess kidney tubular health 4
Frequency of Laboratory Testing
The frequency of laboratory testing for PrEP users in the USA is as follows:
- HIV testing: every 3 months 2
- Syphilis testing: every 3-6 months 2
- Chlamydia and gonorrhea testing: every 3-6 months 2
- Hepatitis B testing: at baseline and as needed 2
- Creatinine level measurement: every 3-6 months 5, 2
- Urine dipstick for protein: every 3-6 months 3
Adherence Monitoring
Adherence to PrEP can be monitored using a urine assay for tenofovir, which can detect tenofovir concentrations in log10 categories between 0 and 10,000 ng/mL 6. This assay can distinguish high and low adherence patterns within the last 48 hours and nonadherence extended over at least 1 week prior to measurement 6.