CD4 Counts ·
CD4 cells are a kind of T-cell, a kind of immune cell that recognises infections and kills them. CD4 cells are the commanding officers of the immune system, telling other immune cells what to do; if they go missing, the whole system breaks down.
The CD4 count measures how many of the key immune cells damaged by HIV you have in your bloodstream. A decline in your CD4 cell numbers is the major cause of immune deficiency, so the CD4 cell count is the most reliable guide to your risk of developing AIDS or becoming ill. It’s expressed as the number of cells in a cubic millimetre (mm3) of blood.
CD4 cell counts in HIV-negative men are about 400 to 1200 cells.
CD4 counts are used to decide when to start treatment. If your CD4 count is high, say above 500, your doctor will continue to monitor you, but for the moment will probably suggest that treatment is not necessary. If your CD4 count drops below 350, your doctor will start to discuss future treatment options for you. It’s strongly recommended you start treatment before it falls below 200-250.
Roughly speaking, when you start treatment your CD4 count should start to go up again.
N.B. CD4 counts go up and down like a yo-yo and no one test will be totally accurate. Doctors will look for a trend and will not change treatment because of one single result.
Another test your doctor may do is the CD4 percentage or CD4 ratio. This measures how many CD4 cells you have relative to another kind of T-cell called the CD8 cells.
A CD4 percentage above 25% is fine: around 20%, you should be starting treatment; below 15% is generally indicative of AIDS.
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