This test looks at the different cells in your blood, including red blood cells, white blood cells, and platelets.

• Red blood cells carry oxygen to other cells in your body. If the level of your red blood cells is too low, you have anemia. Anemia can cause fatigue. Tests that look at your red blood cells include hemoglobin and hematocrit. Hematocrit refers to the percentage of your blood that consists of red blood cells. A normal hematocrit is about 37-47% in females and 40-54% in males.
• White blood cells come in many types, and all are involved in your immune system's effort to keep you healthy (the CD4 cell is a type of white blood cell). High white blood cell counts may indicate that you are fighting an infection. Low counts may put you at risk of getting an infection.
• Platelets help with clotting, so if your platelets fall too low, your blood may not clot well. You may bleed more than usual, for example, when you brush your teeth or shave your skin. As the platelet count falls, the chance of internal bleeding rises.

These tests are usually done every 3 to 6 months, unless your lab values are fluctuating a lot, or you have symptoms of HIV disease. Then the tests may be done more often.