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Learning About Post-Diagnosis HIV Tests

What are post-diagnosis HIV tests?

Soon after you are diagnosed with HIV, you will have other blood tests. These tests help your doctor see how your body is responding to the virus. They also help show how well your treatment is working.

These tests may be done every couple of weeks to every few months. The first set of tests serves as a baseline. Your doctor can compare the results of future tests with the first set. Your doctor will look at the results of several tests over time to see if the infection is getting better with treatment and that the medicines aren't causing any problems.

These tests include the viral load test, a CD4+count, and the HIV drug resistance test. You may also have tests for other infections and to check your health status.

What does the viral load test tell you?

A viral load test measures how much HIV is in your blood.

What it's used for

This test is done to:

  • See how well treatment is working.
  • Guide treatment choices.

How results are reported

Viral load results are reported as the number of HIV copies in a millilitre (copies/mL) of blood. Each virus is called a "copy" because HIV increases by making copies of itself.

What the results mean

With good treatment, the viral load should go down. Within a few months of treatment, the virus should become undetectable. This means that there is very little virus in your blood.

  • If no HIV copies are found, this does not mean that you don't have HIV anymore. It means that the amount of HIV in your blood was too low for the test to detect.

What does the CD4+ count tell you?

HIV destroys CD4+ cells. CD4+ cells are a type of white blood cell. White blood cells are important in fighting infections.

A CD4+ count is a blood test to find the number of CD4+ cells. This number shows if your HIV has progressed to AIDS. It also helps find out if other infections may occur. These other infections are often called opportunistic infections. They occur in people who have weak immune systems. They usually don't occur in people who have healthy immune systems.

What it's used for

CD4+ counts are done to:

  • Track how the HIV infection is affecting your immune system.
  • Help diagnose AIDS.
  • Check your risk of other infections.
  • Decide whether to start treatment to prevent other infections, such as medicines to prevent pneumonia.

How results are reported

Results are reported as the total number of CD4+ cells per microlitre (mcL) of blood. You may also see a percent number. That number is the percentage of white blood cells that are CD4+ cells. The total and the percent numbers go up and down together.

What the results mean

The pattern of CD4+ counts over time is more important than any single count. As the count rises, the healthier your immune system is. As the count drops, it becomes more likely that AIDS will develop.

The ranges listed here are just a guide. The ranges vary from lab to lab. Your lab may use a different range.

A CD4+ count range of:

  • Over 500 cells per mcL is usually found in people who don't have HIV, or who have early HIV. It's also found in people who are being treated for HIV and have undetectable viral loads.
  • 200–500 cells per mcL means your immune system isn't working as well as it could be.
  • Under 200 cells per mcL, in people with HIV infection, means they have AIDS. Low CD4+ counts can also happen in people without HIV. When your CD4+ count is very low, you are at high risk for other infections.

What happens after the test?

Your doctor will talk with you about the results of these tests and what they mean. The doctor will answer any questions you have. The doctor may also:

  • Talk about your current treatment for HIV and suggest any changes that might be needed.
  • Ask you about any trouble you might have with taking your medicines exactly as prescribed.
  • Discuss which of these tests you should have next and when you should have them.
  • Suggest more tests, if you need them.

Follow-up care is a key part of your treatment and safety. Be sure to make and go to all appointments, and call your doctor or nurse advice line (811 in most provinces and territories) if you are having problems. It's also a good idea to know your test results and keep a list of the medicines you take.

Where can you learn more?

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