Essential Testing Before Infectious Disease Referral
After confirming HIV infection with positive antigen/antibody screening and confirmatory testing, you must obtain baseline CD4 count, HIV RNA viral load, and resistance genotype testing before referring to infectious disease. 1, 2
Immediate Laboratory Assessment Required
The following tests should be ordered immediately after confirmed HIV diagnosis:
Core HIV Staging Tests
- CD4 cell count to characterize HIV stage and determine disease progression 1, 2, 3
- HIV RNA level (viral load) to assess baseline viremia and guide treatment decisions 1, 2, 3
- Baseline reverse transcriptase-protease drug resistance genotype testing before initiating antiretroviral therapy 1
General Health Assessment
- Complete blood count to evaluate baseline hematologic status 1
- Comprehensive metabolic panel including kidney function (creatinine, eGFR) and liver function tests (AST, ALT, bilirubin) 1
- Fasting lipid panel for cardiovascular risk assessment 1
- Fasting blood glucose or HbA1c to screen for diabetes 1
- Pregnancy test if applicable 1
Co-infection Screening
- Hepatitis A, B, and C serologies to identify viral hepatitis co-infections 1, 2
- Tuberculosis screening with either tuberculin skin test or interferon-gamma release assay 1
- Sexually transmitted infection screening including syphilis (RPR or VDRL), gonorrhea, and chlamydia 1
- Serum cryptococcal antigen if CD4 count is below 100 cells/μL, even without symptoms 1
Critical Timing Considerations
Do not delay referral to infectious disease while waiting for all laboratory results unless there is preexisting kidney or liver damage or high likelihood of transmitted drug resistance. 1 The infectious disease specialist can initiate antiretroviral therapy promptly, as early treatment improves long-term outcomes and reduces transmission risk. 2
Common Pitfalls to Avoid
- Never initiate antiretroviral therapy yourself before confirmatory testing is complete - treatment should only begin after documented HIV infection 4, 1
- Do not wait for resistance testing results to make the referral - the infectious disease specialist can manage this timing appropriately 1
- Avoid delaying the referral for non-essential testing - comprehensive evaluation can continue after linkage to HIV specialty care 1, 3
Special Populations
For pregnant women with newly diagnosed HIV, immediate referral is critical as antiretroviral prophylaxis may be needed urgently to prevent perinatal transmission, even before all baseline testing is complete. 1
For patients with CD4 counts below 200 cells/μL or opportunistic infections, expedited referral is essential as they require immediate treatment initiation. 5