Health Information and Tools > Patient Care Handouts >  Learning About Post-Diagnosis HIV Tests
Facebook Tweet Share

Main Content

Learning About Post-Diagnosis HIV Tests

What are post-diagnosis HIV tests?

Soon after you are diagnosed with the human immunodeficiency virus (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 3 to 6 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 or worse.

These tests include the viral load test and the CD4 count. Your doctor may order one or both tests.

What is the viral load test?

A viral load test measures how much HIV is in your blood. It measures the amount of the genetic material (RNA) of the virus.

There are several methods that a lab can use to do this test. Each method reports the results in a different way. But all of the methods give you important information about how to treat your disease.

What it's used for

This test is done to:

  • See how well treatment is working.
  • Track changes in the HIV infection.
  • 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

Your numbers may go up or down slightly from test to test. And the specific numbers depend on which method the lab used to measure your viral load. But in general:

  • If your viral load increases over time, it means the infection is getting worse.
  • If the viral load is smaller over time, it means that the infection is being reduced. You are less likely to develop AIDS (acquired immunodeficiency syndrome).
  • If no HIV copies are found, this does not mean that you don't have HIV anymore. It just means that the amount of HIV in your blood was too low for the test to detect. HIV still can be passed to another person even when the viral load can't be detected.

What is the CD4 count?

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 with weak immune systems. They usually don't occur in people with 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 when 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 in a millilitre (cells/mL) 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:

  • 500 to 1,500 cells per microlitre (mcL) is usually found in people who are not infected with HIV. But people who have HIV may have counts over 500 too.
  • More than 350 but less than 500 cells/mcL means that your immune system is starting to weaken.
  • Less than 350 cells/mcL shows a weak immune system and an increased risk for other infections.
  • Less than 200 cells/mcL means you have AIDS and a 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. He or she will answer any questions you have. Your 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?

Go to

Enter X538 in the search box to learn more about "Learning About Post-Diagnosis HIV Tests".

Care instructions adapted under license by your healthcare professional. If you have questions about a medical condition or this instruction, always ask your healthcare professional. Healthwise, Incorporated disclaims any warranty or liability for your use of this information.