Blood tests are important in the medication of HIV infection. The trouble with people is that unless they develop the symptoms, they don't visit the physician for necessary blood exams. Sometimes, the doctors make use of cell count in order to discover if the body has enough strength to fight HIV. For example, doctors measure the number of CD4 cells in our body. Normally, we have 500-1600 cells. Those who are HIV positive and are already exhibiting the symptoms of AIDS have fewer than 200.