Platelet Count: Platelets are a part of the blood that is needed for clotting. They travel to the site of an injury where they "stick" to the injured site and help develop a clot or scab to stop the bleeding. A normal platelet count is 150,000-440,000. Low platelet count (thrombocytopenia) can be caused by HIV infection itself or by certain drugs. Although a platelet count below 150,000 is considered low, most people are not at risk of internal bleeding with counts of 50,000 or even lower. However, because platelets are necessary for blood clotting, the chance of major bleeding rises as the platelet count drops. If your platelet count is low, your doctor may want to change your treatment, or may teach you special precautions to prevent bleeding, like using a soft toothbrush or electric razor.