CD4 Count – Normal (Healthy), HIV, AIDS and Zero Levels
Normal CD4 Count
The CD4+ T-lymphocyte is only one type of white blood cell and is named so due to the presence of CD4 receptors on its surface. It is these surface receptors that allows HIV to bind to the cell and infect it. Read more on HIV and AIDS. Therefore HIV has an affinity for CD4+ T-lymphocytes. The level of CD4+ T-lymphocytes is known as the CD4 cell count or just the CD4 count. It is an indication of the strength of the body’s immune defenses. A normal CD4 count is between 500 to 1500 cells per cubic millimeter (mm3). It is sometimes designated as a percentage. A CD4 percentage of greater than 29% roughly indicates a CD4 count of 500 cells/mm3. This is considered as normal.
HIV CD4 Count
As the body’s CD4+ T-lymphocyte levels drops with HIV infection, the body become more prone to different pathogens. These infections are known as opportunistic infections because it takes advantage of infecting the body at a time when the immune system is weak. A healthy immune system would be able to combat these microorganisms and overcome an infection quickly or prevent the invading pathogen from infecting the body. Therefore the CD4 count does not only indicate the progression of the infection, particularly when monitored along with the viral load, but it also indicates the susceptibility of the body to contract infections.
The CD4 count in HIV can vary from well within the normal range to the very low levels and even reach zero. Even at very low levels, the part of the immune system known as the cell-mediated immunity, has not ceased to function but the body is highly susceptible to infection. Ideally HAART (highly active antiretroviral therapy) should be started at 350 cells/mm3 even if a person is healthy and has not contracted any infections. Guidelines in certain countries advise commencing HAART once the CD4 cell count reaches 500 cells/mm3.
What is a healthy CD4 count for an HIV-positive person?
Ideally a person living with HIV should aim for maintaining a CD4 count above 500 cells/mm3. The higher, the better. A normal CD4 count is within 500 to 1,500 cells/mm3. In terms of CD4 percentage, the normal is considered as between 30% and 60%. Maintaining a health CD4 count is dependent on various factors including :
- proper use of HAART as prescribed
- healthy balanced diet
- exercise and plenty of rest
- stress management
- avoiding alcohol, cigarette smoking and drug use
- limiting sexual contact with multiple, especially infected, partners
AIDS CD4 Count
AIDS is diagnosed once the CD4 count drops below 200 cells/mm3. This correlates to approximately 14% in the CD4 percentage. However the presence of AIDS-defining diseases, a rare set of diseases that are frequently seen with AIDS, is sufficient to diagnose AIDS even if the CD4 count is above 200 cells/mm3.
Zero CD4 Count
Occasionally a person living with HIV records a CD4 count of zero. While the CD4 count can vary, sometimes slightly even within the day or during periods of stress, it is unlikely to reach a level of zero overnight in a person with a normal CD4 count. The decline in CD4 count is gradual and regular monitoring will ensure that a consecutive drop in the cell count or percentage is detected and appropriate measures undertaken to stem a further decrease. A person with a CD4 count of zero (0) can improve and the CD4 count can rise with HAART and appropriate management by a medical professional.
