Can pre‑exposure prophylaxis (PrEP) be started before confirming HIV‑negative status and renal function (creatinine/eGFR) when lab results will take 2–3 days?

Rapid PrEP Initiation Without Confirmed Labs

Yes, you can start PrEP before confirming HIV status and kidney function if you have a negative HIV test from within the past 7 days, or you can initiate after a rapid HIV antibody test on the same day while awaiting confirmatory lab results. 1

HIV Testing Requirements for Rapid Start

The 2025 IAS-USA guidelines provide clear pathways for rapid PrEP initiation:

• If you have a negative HIV test from the past 7 days: Initiate PrEP immediately while awaiting additional diagnostics and safety assessments (including creatinine/eGFR) 1

• If no recent HIV test is available: Perform a rapid HIV antibody test on the same day. Once negative, you can initiate PrEP and send confirmatory laboratory-based antigen/antibody testing. The patient can start PrEP remotely once baseline HIV tests are confirmed negative, assuming good communication 1

The key is that you must have some form of negative HIV test before starting PrEP - either from the past week or a rapid test performed that day. You cannot start PrEP with zero HIV testing.

Kidney Function Considerations

Renal function testing can be deferred while initiating PrEP in the rapid start scenario. The guidelines explicitly state you can initiate while "awaiting further diagnostics and safety assessments" 1. This is supported by real-world evidence:

• A Polish cohort study of 308 PrEP initiations found rapid PrEP start was safe and feasible, with contraindications being rare. Median creatinine increased minimally (0.93 to 0.95 mg/mL) after 1 month - statistically significant but not clinically meaningful 2

• Complex kidney situations (eGFR <60 mL/min/1.73m²) occurred in only 0.25 per 100 person-years in a French cohort, with most cases manageable 3

Practical Algorithm for Your 2-3 Day Lab Delay Scenario

Day 1 (Initial Visit):

1. Perform rapid HIV antibody test
2. If negative → Start PrEP immediately
3. Send laboratory-based antigen/antibody test + HIV RNA test (if available)
4. Send creatinine/eGFR
5. Provide 30-day supply

Day 3-4 (When Labs Return):

1. Review confirmatory HIV testing
2. Review renal function
3. If eGFR 30-60 mL/min → Switch to TAF/FTC 1
4. If eGFR <30 mL/min → Discontinue and reassess
5. Continue PrEP if all results appropriate

Critical Caveats

Do not initiate PrEP if:

• Signs/symptoms of acute HIV infection are present (fever, rash, lymphadenopathy, pharyngitis)
• Known substantial HIV exposure within past 72 hours → Use 3-drug PEP regimen instead 1
• Patient cannot be reliably contacted for follow-up results

Follow-up testing is mandatory:

• If HIV RNA testing unavailable at baseline, repeat antigen/antibody testing 1 month after starting tenofovir-based PrEP 1
• This catches acute HIV infections that may have been in the window period

Special Populations

For individuals over 50 years or with baseline eGFR <90 mL/min/1.73m², there is higher risk of complex kidney situations (HR 13 and HR 34 respectively) 3. However, this does not preclude rapid start - it simply requires closer monitoring once results return.

The evidence strongly supports that a 2-3 day delay for comprehensive lab results should not prevent PrEP initiation when rapid HIV testing is negative. The risk of missing a prevention opportunity outweighs the minimal risk of short-term PrEP use before full laboratory assessment.