Q and A

Question

What is a normal CD4 count, CD4% and CD4:CD8 ratio?

Answer

After finding out you are HIV positive, your doctor will run several blood tests.

One will be for your immune system and will include your CD4 and CD8 count. Of these, the CD4 count is the most important main result but the CD4% and CD4:CD8 ratio are also sometimes useful.

This Q&A include information about these cels and about interpreting the test results.

CD4 cells are a type of blood cell that is part of your immune system. They are a type of white blood cell (lymphocyte). CD4 cells are sometimes called T-helper cells or T-cells

There are two main types of T-cells.

  1. CD4 cells, also called T4 cells, are “helper” cells. They lead the attack against infections.
  2. CD8 cells, (T8 cells), are “suppressor” cells that complete the immune response. CD8+ cells can also be “killer” cells that kill cancer cells and other cells that are infected by a virus.

CD4 and CD8 counts

The normal ranges for CD4 and CD8 counts vary depending on the lab and test. On average, the normal CD4 range for an HIV negative person is between 460 and 1600. This is an average. Anywhere in this range is good.

Although generally a higher CD4 is good, an HIV negative person with a normal CD4 count of 1200 is not more healthy than someone whose normal count is 400.

The exact CD4 count is not so important. CD4 counts can vary from day to day and even from hour to hour. So the general CD4 result is more important than the exact number.

A normal CD8 range is from 150 to 1000. This test is not used as much but the results come together. It is more important to know your CD4 count than your CD8 count.

CD4 percentage (CD4%)

If you get a CD4 count that is ever unexpectedly high or low, then your CD4% (CD4 percentage) can show whether this is a real change in immune function. The CD4% is a more stable marker than the absolute CD4 count.

The CD4 percentage refers to percentage of total lymphocytes that are CD4 cells. If your test reports CD4% = 34%, that means that 34% of your lymphocytes are CD4 cells.

The average normal CD4% for HIV negative adults is about 40%. However, as with CD4 counts and other test, the range for a “normal” result in an HIV negative person is also wide – from about 25% to 65%.

CD4:CD8 ratio

The CD4:CD8 ratio is also sometimes used, but less often. This is a measure of how balanced your immune function is. This calculated by dividing the CD4 result by the CD8 result.

In HIV negative people, the normal range for the CD4:CD8 ratio is between 0.9 and 1.9. This means that there are about 1 to 2 CD4 cells for every CD8 cell.

When not on HIV treatment, just like the CD4 count and CD4%, the CD4:8 ratio drops over time. Eventually, unless you start treatment, there will be more CD8 cells than CD4 cells (i.e. the ratio drops to less than 1.0).

The CD4:CD8 ratio might be better at predicting future risk in people whose CD4 count is high (above 500 cells/mm3). However, not all studies agree on this.

Other studies have shown that starting ART soon after HIV infection has a much higher chance of keeping the CD4:CD8 ratio higher than 1.0.

Note: this answer was last updated in January 2018 from a post that was originally published in December 2006.

198 comments

  1. Roy Trevelion

    Hi Sudha, The only way to improve your CD4 count is to start HIV treatment (ART). Here are frequently asked questions about the CD4 count. Starting ART can get your viral load to drop dramatically. And this can help your CD4 count to recover.

  2. Sudha

    How should i improve my cd4 count

  3. Lisa Thorley

    Hi JJ,

    Your friends CD4 count is very low. He is going to need specialist treatment as it sounds like he has opportunistic infections. He is going to need to start ART and ideally as soon as possible.

    Its very possible the docotors are trying to ascertain if he’s got Cryptococcal meningitis, this is what the spin tap test will be used for. This is something that they should be able to treat. There’s more about this here:

    http://i-base.info/ttfa/5-opportunistic-infections-ois-and-coinfections/12-cryptococcal-meningitis/

    The MRI is to see if there’s been any damage to his brain.

    Because his CD4 is low he should ideally be following the advice that’s here:

    http://i-base.info/qa/4643

    He’s going to need some support.

  4. JJ

    We just found out a friend of mine is HIV positive and has been for 11 years and has gone untreated has been active with his partner the last 2 years. He is currently in the hospital very ill, having trouble walking, with his speech and incontinence: his cd4 is 3 continues to run a high fever. Currently not taking meds. The doctors are trying to determine the additional infections with a spinal tap and a mri of the brain. Does this mean he is at the AIDS stage of the disease? What will the spinal tap show us and what additional questions should we ask. He has kept this information to himself until we had to bring him to the ER.

  5. Roy Trevelion

    Hi Zukisa, Treatment for HIV reduces the virus in the blood to tiny amounts. So being undetectable (when the viral load is less than 50 copies) can protect the baby from HIV. Many HIV positive mothers have had healthy HIV negative babies. You can read about it here. And here is the guide to HIV pregnancy and women’s health.

  6. Zukisa

    Hi,why is it possible to prevent a child from getting infected from a mother during pregnancy but you can’t treat hiv how is this possible because basically a child is growing with the blood of the mother it is conceived by the infected cells?

  7. Lisa Thorley

    Hi John,

    As you’ve been on meds for 4 months you should be out of the IRIS period.

  8. John

    Thank you for your valuable reply. I am in 4 months of art and no iris till now. does it mean that I am out of iris period?

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