What blood work is needed before starting Truvada (emtricitabine and tenofovir disoproxil fumarate) for Pre-Exposure Prophylaxis (PrEP)?

Required Blood Work Before Starting Truvada (Emtricitabine/Tenofovir Disoproxil Fumarate) for PrEP

Before initiating Truvada for PrEP, patients must undergo HIV testing with a combination antigen-antibody assay, serum creatinine with estimated creatinine clearance, hepatitis B surface antigen testing, and comprehensive STI screening. 1, 2

Essential Pre-Initiation Laboratory Tests

HIV Testing

• HIV combination antigen-antibody assay (preferred) 1, 2
• HIV RNA testing may be needed to exclude acute HIV infection in high-risk individuals 1
• Testing must be performed within 7 days before starting PrEP 1

Renal Function Assessment

• Serum creatinine with estimated creatinine clearance calculation 1, 2
• TDF-based PrEP is contraindicated if creatinine clearance is <60 mL/min 1, 2

Hepatitis Screening

• Hepatitis B surface antigen (HBsAg) 1, 2
  • Patients with chronic hepatitis B require additional monitoring due to risk of hepatitis flares if PrEP is discontinued 3
• Hepatitis A antibody testing (to determine vaccination needs) 1
• Consider hepatitis C antibody testing, especially for high-risk individuals 1

STI Screening

• Comprehensive STI screening based on sexual practices 1, 2:
  • Syphilis serology
  • Gonorrhea (urine, throat, rectal, vaginal as appropriate)
  • Chlamydia (urine, throat, rectal, vaginal as appropriate)

Additional Baseline Tests

• Pregnancy test for women of childbearing potential 2
• Consider baseline bone mineral density in patients with risk factors for osteoporosis 1

Important Clinical Considerations

Contraindications

• Active HIV infection
• Creatinine clearance <60 mL/min 1
• Osteopenia or osteoporosis (relative contraindication) 1

Special Populations

• For patients with chronic hepatitis B: Use Truvada with caution due to risk of hepatitis flares if discontinued 1, 3
• For patients with borderline renal function: Consider more frequent monitoring of creatinine clearance 1, 2

Follow-Up Monitoring Schedule

After initiating PrEP, the following monitoring schedule is recommended:

• 1-month follow-up:

  • Assess adherence and tolerability
  • Rule out primary HIV infection 1

• Every 3 months:

  • HIV testing (combination antigen-antibody assay) 1, 2
  • STI screening 1, 2
  • Adherence assessment 1

• Every 6 months:

  • Creatinine and estimated creatinine clearance 1, 2
  • HCV serology for high-risk individuals 1

Critical Safety Considerations

1. PrEP prescriptions should not exceed 90 days without interval HIV testing 1

2. More frequent creatinine monitoring is recommended for patients with:

   • Age >50 years
   • Hypertension
   • Diabetes
   • Borderline renal function 1, 2

3. Patients with suspected acute HIV infection while on PrEP require immediate confirmatory testing with HIV RNA and genotype testing if confirmed 1

4. Truvada has a good safety profile but requires vigilant monitoring for potential side effects affecting renal function, liver enzymes, and bone mineral density 4