Laboratory Testing Before Refilling Truvada for PrEP
Before refilling a Truvada prescription for PrEP, you must obtain: HIV testing (at minimum every 3 months), creatinine clearance (every 6 months after the initial 3-month check), STI screening (every 6 months), and for women, a pregnancy test at each visit. 1
Required Testing at Each Refill Visit
HIV Status Confirmation (Every 2-3 Months)
- HIV antibody test or fourth-generation antigen/antibody test is mandatory before each refill 2, 1
- The FDA label explicitly requires screening at least every 3 months while taking Truvada for PrEP 1
- The 2025 IAS-USA guidelines recommend testing every 2-3 months 3
- If the patient has symptoms consistent with acute HIV infection (fever, fatigue, myalgia, rash), delay refilling and use an HIV RNA test or repeat testing in one month 1
Critical pitfall: Drug-resistant HIV variants can emerge if PrEP is continued in someone with undetected acute HIV infection, since Truvada alone is not a complete treatment regimen 1
Renal Function Monitoring
- Check serum creatinine and calculate creatinine clearance at 3 months after initiation, then every 6 months thereafter 2, 1
- Do not refill if creatinine clearance falls below 60 mL/min—Truvada for PrEP is contraindicated at this level 1
- For patients with mild renal impairment (CrCl 50-80 mL/min), perform routine monitoring of estimated creatinine clearance, serum phosphorus, urine glucose, and urine protein 1
STI Screening (Every 6 Months)
- Test for bacterial STIs every 6 months, even if asymptomatic 2
- The 2025 IAS-USA guidelines recommend quarterly STI screening of contact sites and blood syphilis testing 3
- Treat any identified STIs before refilling 2
Pregnancy Testing (For Women, Each Visit)
- Pregnancy test at each follow-up visit 2
- If pregnant, discuss continued use with the patient and prenatal care provider 2
- The FDA label states not to prescribe to women who are breastfeeding 2
Additional Monitoring at Each Visit
Adherence and Risk Assessment
- Evaluate PrEP medication adherence at each visit—effectiveness is strongly correlated with adherence 1
- Assess risk behaviors and provide risk-reduction counseling every 2-3 months 2
- Assess for STI symptoms even between scheduled screening intervals 2
Hepatitis B Considerations
- While hepatitis B screening is recommended at initiation 2, if active hepatitis B was diagnosed initially, monitor hepatic function closely if considering discontinuation, as severe acute exacerbations can occur 1
Practical Algorithm for Refills
At 2-3 month refill visits:
- HIV test (mandatory)
- Pregnancy test (women)
- Adherence assessment
- Risk behavior assessment
- STI symptom check
At 6-month refill visits (add to above):
- Creatinine clearance calculation
- Comprehensive STI screening (all contact sites + syphilis)
- Serum phosphorus, urine glucose, urine protein (if mild renal impairment)
At 3-month mark only:
- First renal function check after initiation
Common pitfall: Recent data shows only 35.3% of PrEP initiators receive recommended laboratory-based HIV testing 4. While point-of-care rapid tests facilitate access, the FDA label and guidelines emphasize laboratory-based confirmation, particularly to detect acute infection that rapid antibody tests may miss.