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Guides Introduction to combination therapy

CD4 and viral load: two essential blood tests

Your CD4 and viral load results are the main tests used to monitor your health.

CD4 tests

CD4 tests measure your immune system. Results are given as cells/mm3. Above 500 is considered ‘normal’

  • Your CD4 count is important for deciding when to start treatment.
  • Even if you start with a very low CD4 count, once you start treatment, your immune system can become strong enough for your body to be able to recover from HIV-related illnesses.

Viral load tests

Viral load tests tell you how much virus is in a small sample of blood. Results are given as copies/mL.

  • If you are on treatment, viral load tests show how well your treatment is working. You need to aim to get this ‘undetectable’. This means less than 50 copies/mL.
  • Once viral load is undetectable, this test shows whether the drugs continue to work.
  • If the viral load  doesn’t become undetectable or it increases later, it means the drugs may not be working or that you may not be taking them correctly.
  • Any unusual result should be checked with a second test before making treatment changes.
  • A high viral load (over 100,000 copies/mL) can be a reason to start treatment at any CD4 count.

July 2010

Decisions relating to your treatment should always be taken in consultation with your doctor. Information in this guide is intended to support those discussions.

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