CD4 Count

This is a test used to measure the strength of your immune system if you've been diagnosed with HIV infection.

This test measures the number of CD4 cells (also known as T-helper cells) in your blood and assesses the status of your immune system. CD4 cells are a type of white blood cell that fights infection, and they play an important role in your immune system. They help to identify, attack, and destroy specific bacteria, fungi, and other germs that affect the body. CD4 cells are made in the spleen, lymph nodes, and thymus gland, and they circulate throughout the body in the bloodstream. CD4 cells are a major target for HIV, which binds to the surface of CD4 cells, enters them, and either reproduces immediately, killing them in the process, or remains in a resting state, reproducing later. As the HIV virus gets into the cell and replicates, the number of CD4 cells in the blood gradually declines. As HIV disease progresses, the CD4 count will go down and as treatment reduces the progression, the CD4 count will go back up.

The CD4 count tells your caregivers how strong your immune system is, how far HIV disease has advanced (the stage of the disease), and helps predict the risk of complications and debilitating infections. The CD4 count is most useful when it is compared with the count obtained from an earlier test.

The CD4 count is used in combination with the viral load test, which measures the level of HIV in the blood, to determine the staging and outlook of the disease.

PREPARATION FOR TEST

No preparation is required.

NORMAL FINDINGS

T cells

  • Percent: 60-95

  • Number of Cells/microL: 800-2500

T-helper (CD4) cells

  • Percent: 60-75

  • Number of Cells/microL: 600-1500

T-suppressor (CD8) cells

  • Percent: 25-30

  • Number of Cells/microL: 300-1000

B cells 

  • Percent: 4-25

  • Number of Cells/microL: 100-450

Natural killer cells 

  • Percent: 4-30

  • Number of Cells/microL: 75-500

CD4/CD8 ratio: Greater than 1

Ranges for normal findings may vary among different laboratories and hospitals. You should always check with your doctor after having lab work or other tests done to discuss the meaning of your test results and whether your values are considered within normal limits.

MEANING OF TEST

Your caregiver will go over the test results with you and discuss the importance and meaning of your results, as well as treatment options and the need for additional tests if necessary.

OBTAINING THE TEST RESULTS

It is your responsibility to obtain your test results. Ask the lab or department performing the test when and how you will get your results.