HIV Stages & Lab Monitoring

A client's CD4 count is 180 cells/mm³ but they feel fine. Do they have AIDS? The answer depends on whether you understand staging — not symptoms.

HIV staging drives every treatment decision and prophylaxis trigger. Stage 1 (CD4 ≥ 500 cells/mm³). Stage 2 (chronic/clinical latency): CD4 200–499 cells/mm³. Stage 3 (AIDS): CD4 < 200 cells/mm³ OR presence of an AIDS-defining condition, regardless of CD4 count. A client can be asymptomatic at any stage — staging is lab-based, not symptom-based. Two labs anchor monitoring: the CD4 count reflects immune function and guides prophylaxis decisions, while the viral load (HIV RNA) measures treatment effectiveness. A rising viral load signals nonadherence or drug resistance. The goal of antiretroviral therapy is an undetectable viral load (< 20–50 copies/mL depending on assay), which means the virus cannot be sexually transmitted (U=U: Undetectable = Untransmittable). CD4 counts are monitored every 3–6 months; more frequently at diagnosis or with regimen changes. Prophylaxis thresholds are testable: start PCP prophylaxis (trimethoprim-sulfamethoxazole) when CD4 < 200; start MAC prophylaxis when CD4 < 50.

Key Distinctions

Don't confuse CD4 count (immune status, guides prophylaxis) with viral load (disease activity, guides treatment effectiveness) — they answer different clinical questions. Students assume AIDS requires symptoms, but a CD4 < 200 alone qualifies as Stage 3 even in an asymptomatic client. A low viral load doesn't mean the immune system has recovered — CD4 may still be dangerously low.

Clinical Pearl

CD4 tells you WHERE you are (staging and prophylaxis). Viral load tells you WHERE you're headed (treatment working or failing). Track both, confuse neither.