A CD4+ count is a blood test to determine how
immune system is working in people who have been
human immunodeficiency virus (HIV). CD4+ cells are a
type of white blood cell. White blood cells are important in fighting
infections. CD4+ cells are also called T-lymphocytes, T-cells, or T-helper
HIV infects CD4+ cells. The number of CD4+ cells helps
determine whether other infections (opportunistic infections) may occur. The pattern of CD4+ counts over time is more
important than any single CD4+ value because the values can change from day to
day. The CD4+ pattern over time shows the effect of the virus on the immune
system. In people infected with HIV who are not getting treated, CD4+ counts
generally decrease as HIV progresses. A low CD4+ count usually indicates a
weakened immune system and a higher chance of getting opportunistic
CD4+ counts are done to:
A CD4+ cell count taken at the time you are diagnosed
serves as the baseline against which future CD4+ cell counts will be compared.
Your CD4+ cell count is monitored every 3 to 6 months, depending on your health
status, previous CD4+ cell counts, and whether you are taking
antiretroviral therapy (ART)
Before you have this test, you may have
the opportunity to meet with a counselor so that you understand what the test
results could mean about your HIV infection.
The health professional drawing blood
You may feel nothing at all from the
needle puncture, or you may feel a brief sting or pinch as the needle goes
through the skin. Some people feel a stinging pain while the needle is in the
vein. But many people do not feel any pain (or have only minor discomfort) after
the needle is positioned in the vein. The amount of pain you feel depends on
the skill of the health professional drawing the blood, the condition of your
veins, and your sensitivity to pain.
There is very little risk of complications from
having blood drawn from a vein.
A CD4+ count is a blood test to determine
how well the immune system is working in people who have been diagnosed with
human immunodeficiency virus (HIV). CD4+ cell count
results are generally available in 1 to 3 days, depending on the lab.
The normal values listed here—called a reference range—are just a guide. These ranges vary from lab to lab, and your lab may have a different range for what's normal. Your lab report should contain the range your lab uses. Also, your doctor will evaluate your results based on your health and other factors. This means that a value that falls outside the normal values listed here may still be normal for you or your lab.
CD4+ cell counts in people who
are not infected with HIV usually range from 600 to 1,500 cells per
A CD4+ cell count greater than 350 but less than 500 cells/mcL means that the immune system is beginning to weaken.
A CD4+ cell count of fewer
than 350 cells/mcL indicates a weak
immune system and an increased risk for opportunistic
A CD4+ cell count of fewer
than 200 cells/mcL indicates
acquired immunodeficiency syndrome (AIDS) and a high
risk for opportunistic infections.
As the CD4+ count drops, it becomes more likely that
acquired immunodeficiency syndrome (AIDS) will develop.
Reasons you may not be able to
have the test or why the results may not be helpful include:
CitationsPagana 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 (2012). Guidelines for the Use of Antiretroviral Agents
in HIV-1-Infected Adults and Adolescents. Available online: http://aidsinfo.nih.gov/contentfiles/lvguidelines/adultandadolescentgl.pdf.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 ConsultedFischbach 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 (2011). Guidelines for the Use of Antiretroviral Agents in HIV-1-Infected Adults and Adolescents. Available online: http://www.aidsinfo.nih.gov/ContentFiles/AdultandAdolescentGL.pdf.
November 7, 2012
E. Gregory Thompson, MD - Internal Medicine & Peter Shalit, MD, PhD - Internal Medicine
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