HIV | Necessary controls

The analysis of your blood gives information about the current status of your immune system and the course of the HIV-infection. The T- helper cell count (CD4-positive cell count) shows the degree of impairment of your immune system. The viral load (HIV-RNA) indicates how strongly the virus replicates in the body, which correlates with the time to deteriotation of the immune system.

A comprehensive laboratory assessment of the HIV-infection always includes:

  • cellular immune status
  • viral load (HIV-RNA)

Immune status

The determination of the cellular immune status measures changes of the lymphocytes, a subgroup of the white blood cells. The normal value of the relative cell count of the helper cells is above 30 %. This means that the immune system is normal when at least one third of the lymphocytes are helper cells. If this value is below 15 % the immune system is strongly impaired.

The absolute number of T-helper cells is counted per microliter of blood. The normal range of helper cells is between 500 and 1200 cells/µl. Moreover, the ratio between T-helper cells and the so-called suppressor cells (the CD4/CD8 ratio) is important in addition to the absolute and relative helper cell count (range of normal 0.8 – 1.5).

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Viral load

In order to assess the viral load (HIV-RNA) the number of viral copies per microliter of blood is measured by real-time polymerase chain reaction with an ultrasensitive assay.

In general a viral load (HIV-RNA) below 10,000 copies/ml is considered low, a viral load above 100,000 copies/ml high. However, it is essential to evaluate the viral load together with the immune status and the general state of health.

The aim of an antiretroviral treatment is to suppress the viral load below the limit of detection as long as possible.

If HIV viral load is below the limit of detection this does not mean that the virus is no longer existent in the blood or in other body fluids. Even without detectable viral load in the blood HIV can be transmitted by unprotected sexual contacts or blood contacts e.g. by needle-sharing or blood transfusion.

Infections can cause reductions of helper cells and increases in viral load. These values normalize after the infection has been passed through in most of the cases. Vaccination can lead to a short and reversible increase in viral load.

Other factors influencing the number of T-helper cells in a negative way are

  • excessive alcohol consumption
  • drug use
  • malnutrition
  • extensive sunbathing
  • diabetes mellitus
  • chronic hepatitis B or C
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