What it means
CD4 cells are helper T cells that direct the immune response. HIV kills them over time, so the count shows how strong the immune system is. In a person with HIV, a count below 200 cells/mm³ defines AIDS and greatly raises the risk of opportunistic infections. It is followed along with the viral load to see how well treatment is working.
For the nurse
Teach infection prevention to clients with low counts, and give preventive antibiotics as ordered. A rising count on treatment is a good sign.
At a glance
| Normal range | About 500–1,500 cells/mm³ [0.5–1.5 × 10⁹/L]; each lab sets its own range. |
|---|---|
| Critical range | Below 200 cells/mm³ in HIV defines AIDS. |
| Also written | CD4 T-cell count, CD4 cell count, CD4+ T-cell count |
Related terms
immunodeficiency
A state in which the immune system is weaker than normal and cannot fight infection well.
zidovudine
An antiretroviral drug used with other HIV drugs, and to lower the chance of HIV passing from a pregnant person to the baby.
ritonavir
An HIV protease inhibitor, now used mostly in low doses to raise the blood levels of other antiviral drugs.