CD4 count - meaning and definition
AlsoCD4 cell countT-cell countCD4CD4 cellsT helper cells
Not yet reviewed by a clinician. This health entry was written from the public-health sources listed below and is general information only. It is not medical advice.
Definition
A CD4 count measures the number of CD4 cells, a type of white blood cell, in a sample of blood; it shows how well the immune system is coping with HIV.
At a glance
- A CD4 count measures the number of CD4 cells, a type of white blood cell, in the blood.
- HIV attacks CD4 cells, so without treatment their number falls.
- A very low count means a higher risk of serious infections.
- With effective treatment the CD4 count usually rises and stabilises.
- Once someone is stable on treatment, viral load is often checked more regularly than CD4.
In detail
HIV attacks CD4 cells, so without treatment their number gradually falls. A very low count means a higher risk of serious infections and is one way advanced HIV disease is identified.
With effective treatment the CD4 count usually rises and stabilises. Once someone is stable on treatment, viral load is often checked more regularly than CD4.
In a sentence
- Her CD4 count has gone up steadily since she started treatment.
- The HIV clinic report listed both the CD4 count and the viral load.
Where the word comes from
"CD" stands for "cluster of differentiation", a naming system scientists use for markers on the surface of cells.
Not to be confused with
- Viral load
Viral load measures the amount of virus, not immune cells.
Common questions
What is the difference between a CD4 count and viral load?
A CD4 count shows how well the immune system is coping, while viral load measures how much virus is in the blood. Both help track HIV and its treatment.
Can a CD4 count go back up?
Yes. With effective HIV treatment the CD4 count usually rises and then stabilises. An HIV clinic can explain individual results.