What laboratory tests should be monitored in HIV (Human Immunodeficiency Virus) patients?

Laboratory Monitoring in HIV Patients

HIV patients require regular laboratory monitoring of CD4 counts, viral load, and additional tests to assess disease progression, treatment efficacy, and screen for comorbidities.

Core HIV Disease Monitoring Tests

Initial Diagnosis/Baseline Testing

• HIV confirmation testing: Serologic testing to confirm HIV diagnosis if no documentation exists 1
• CD4 cell count and percentage: Essential for disease staging and determining need for opportunistic infection prophylaxis (A-I) 1
• HIV viral load (HIV RNA): Establishes baseline for monitoring treatment response 1
• HIV resistance testing: Genotype testing recommended for all newly diagnosed patients to detect transmitted drug resistance (A-III) 1
• HLA-B*5701 testing: Required before prescribing abacavir 1
• Coreceptor tropism assay: Recommended prior to prescribing CCR5 entry inhibitors 1

Safety Laboratory Tests

• Complete blood count with differential: Monitors for medication side effects and HIV-related cytopenias 1
• Chemistry panel: Including electrolytes, BUN, creatinine, liver function tests (ALT, AST, bilirubin, alkaline phosphatase), albumin 1
• Fasting lipid profile: Baseline and monitoring for metabolic complications 1
• Fasting glucose/HbA1c: Screens for diabetes and metabolic complications 1
• Urinalysis: Screens for proteinuria and hematuria 1, 2
• G6PD screening: In appropriate racial/ethnic groups 1

Ongoing Monitoring Schedule

• CD4 count and viral load: Every 3-4 months after starting therapy (B-II) 1
  • Once viral suppression achieved and stable for 1 year: Can monitor every 6 months (AIII) 1
  • CD4 counts >650 cells/mm³ with treatment threshold of 200: Can monitor yearly 3
• HIV viral load: 4-8 weeks after starting ART to assess initial response 1
• Resistance testing: Indicated if viral load not declining after 4-6 weeks of therapy or viral rebound occurs 1

Coinfection and Comorbidity Screening

Infectious Disease Screening

• Syphilis serology: Annual screening recommended 1, 2
• Other STI screening: Annual testing for gonorrhea and chlamydia 1, 2
• Tuberculosis screening: Annual testing in high-risk patients 1, 2
• Viral hepatitis screening: Hepatitis A, B, and C antibodies 1
• Toxoplasma gondii serology: Baseline and as indicated 1
• Cryptococcal antigen: Baseline screening for patients with CD4 <100 cells/μL (AIIa) 1
• CMV and herpesvirus screening: Consider in appropriate patients 1

Cancer Screening

• Cervical Pap smear: Annual screening in all women after 2 normal Pap tests in first year after diagnosis 1, 2
• Anal cytology: Consider in appropriate patients 1
• Mammography: Annual screening in women ≥50 years 1, 2
• Colorectal cancer screening: Age-appropriate screening 1, 2

Other Health Maintenance

• Bone densitometry: Baseline in postmenopausal women and those with risk factors for bone loss 1, 2
• Depression screening: Annual screening recommended 1
• Serum testosterone: Consider in men with fatigue, weight loss, libido issues 1

Clinical Considerations

Importance of Viral Load Monitoring

• Viral load is superior to CD4 count in predicting mortality in patients on ART 4
• Viral load monitoring is critical for:
  • Detecting early treatment failure
  • Assessing adherence to therapy
  • Determining when to change treatment regimens 5

CD4 Count Considerations

• CD4 monitoring is essential to determine need for opportunistic infection prophylaxis 1
• Two baseline CD4 measurements may be useful before making treatment decisions due to natural variability (C-III) 1
• CD4:CD8 ratio is not recommended for clinical decision making (B-III) 1

Common Pitfalls to Avoid

1. Overreliance on CD4 counts alone: Viral load is a more sensitive indicator of treatment failure 4
2. Insufficient monitoring frequency: Can miss early treatment failure
3. Excessive monitoring: Unnecessary testing in stable patients with good viral suppression 6
4. Inconsistent viral load assays: Use the same assay throughout patient care when possible 1
5. Failure to consider transient viral load elevations: Can occur with vaccinations and intercurrent illnesses 1

Special Considerations

• Pregnant women may require more frequent monitoring
• Patients with comorbidities (hepatitis, renal disease) need additional targeted monitoring
• Laboratory results should be standardized for reporting to facilitate comparison across time and between facilities 1