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    CD4+ Count

    What Affects the Test

    Reasons you may not be able to have the test or why the results may not be helpful include:

    • The time of day when the CD4+ is measured. CD4+ counts may be lower in the morning.
    • Illnesses, such as pneumonia, herpes simplex infection, or influenza.
    • Refrigeration of the blood sample.
    • Medicines, such as corticosteroids and chemotherapy medicines.

    What To Think About

    • The pattern of CD4+ counts over time is more important than any single CD4+ value. CD4+ counts typically decrease as HIV progresses.
    • The CD4+ cell count is often done with viral load testing to measure the effectiveness of antiretroviral therapy. The viral load test measures the actual amount of HIV in the blood, which is a good indicator of how well medicines are controlling the HIV infection. In some cases, viral load testing may be done instead of the CD4+ count. To learn more, see the topic Viral Load Measurement.
    • Medical experts recommend that people begin antiretroviral therapy for HIV as soon as they know that they are infected.2, 3 Treatment is especially important for pregnant women, people who have other infections (such as tuberculosis or hepatitis), and people who have symptoms of AIDS.
    • Because total CD4+ count can vary throughout the day, many doctors also monitor the number of CD4+ cells in relation to the total number of lymphocytes. This measurement is called the CD4+ percentage.
    • Another measurement that may be used is the CD4 count (T helper cells) in comparison with the CD8 count (T suppressor cells). This is called the CD4/CD8 ratio. All of these measurements can help determine the effectiveness of HIV treatment.
    • Testing for HIV infection is a different test. To learn more, see the topic Human Immunodeficiency Virus (HIV) Test.

    Citations

    1. Pagana KD, Pagana TJ (2010). Mosby’s Manual of Diagnostic and Laboratory Tests, 4th ed. St. Louis: Mosby Elsevier.

    2. U.S. Department of Health and Human Services Panel on Antiretroviral Guidelines for Adults and Adolescents (2013). Guidelines for the Use of Antiretroviral Agents in HIV-1-Infected Adults and Adolescents. Available online: http://www.aidsinfo.nih.gov/ContentFiles/AdultandAdolescentGL.pdf.

    3. Thompson MA, et al. (2012). Antiretroviral treatment of adult HIV infection: 2012 recommendations of the International Antiviral Society-USA Panel. JAMA, 308(4): 387-402.

    Other Works Consulted

    • Fischbach FT, Dunning MB III, eds. (2009). Manual of Laboratory and Diagnostic Tests, 8th ed. Philadelphia: Lippincott Williams and Wilkins.

    • Pagana KD, Pagana TJ (2010). Mosby’s Manual of Diagnostic and Laboratory Tests, 4th ed. St. Louis: Mosby Elsevier.

    • U.S. Department of Health and Human Services Panel on Antiretroviral Guidelines for Adults and Adolescents (2013). Guidelines for the Use of Antiretroviral Agents in HIV-1-Infected Adults and Adolescents. Available online: http://www.aidsinfo.nih.gov/ContentFiles/AdultandAdolescentGL.pdf.

    WebMD Medical Reference from Healthwise

    Last Updated: June 04, 2014
    This information is not intended to replace the advice of a doctor. Healthwise disclaims any liability for the decisions you make based on this information.

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