Understanding CD4 Cells and CD4 Cell Tests
The CD4 cell test is a simple blood test ordered by your health care provider. When you first start receiving care for HIV, you should get a "baseline" CD4 cell test. This baseline test gives a picture of your immune system when you first enter into care. Later tests can be compared against this first result to see how things are changing over time and with treatment.
It is important to get your CD4 count checked about every three to six months -- or as often as your health care provider recommends. You will need more frequent CD4 cell tests if your count is low or falling, or if you are starting or changing treatment.
Many factors can affect your CD4 count, including the time of day, level of stress, your menstrual cycle, and infections such as the flu. If you get a result back that surprises you or your health care provider, he or she will probably want you to get a second test. The second test would confirm any unexpected results or show that the first test's results were random -- the result of lab error or an unimportant occurrence. Try not to worry too much about a single abnormal test result; trends over time are usually more important.
In addition to your CD4 cell count, your health care provider will want to check your CD4 percentage. This number tells you what percent of your total white blood cells are CD4 cells. A normal CD4 cell percentage is about 30 to 60 percent.
The CD4 percentage is sometimes a more reliable measurement than the CD4 count because it tends to change less between measurements. While the CD4 percentage gives information about the health of your immune system, the CD4 count is the preferred measurement for assessing progression of HIV disease. Currently, treatment guidelines are based on CD4 counts and not on CD4 percentage.
If you begin treatment when your CD4 count and percentage are low (CD4 count <200), it may take longer for your CD4 numbers to increase. However, if your viral load is below detectable levels, then you can be encouraged that the virus is not growing or spreading. Sometimes watching your CD4 cells and percentage increase can take lots of patience and waiting time.
Because HIV infects and kills CD4 cells, CD4 counts usually drop as HIV disease gets worse. Taking effective combinations of HIV drugs may stop your CD4 count from dropping and your HIV disease from progressing.
Your CD4 count is an important indicator of the health of your immune system. Keeping track of the trends in your CD4 count can help you and your health care provider make decisions about starting and changing treatment. Getting regular CD4 cell tests -- along with viral load tests and other blood tests to check for treatment side effects -- is an important way to take charge of your health.
This article was provided by The Well Project. Visit The Well Project's Web site to learn more about their resources and initiatives for women living with HIV. The Well Project shares its content with TheBody.com to ensure all people have access to the highest quality treatment information available. The Well Project receives no advertising revenue from TheBody.com or the advertisers on this site. No advertiser on this site has any editorial input into The Well Project's content.
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