The five blood tests include the number of white blood cells, the number of red blood cells, the pressure of red blood cells, the concentration of hemoglobin and the number of platelets. There is a normal range for the number of white blood cells, and anything above or below the normal range is considered abnormal. Decreased white blood cell counts can be seen in viral infections and after patients have received radiotherapy. In some patients with leukemia, the white blood cell count may be abnormally high. Increased erythrocyte count is most commonly associated with chronic hypoxic diseases such as chronic obstructive pulmonary disease, and residents of highland areas may also experience abnormally high erythrocyte counts. Hemoglobin concentration is a common indicator to determine whether the human body is anemic. Platelet count above or below the normal range is also abnormal, and a decrease in platelet count may cause bleeding symptoms in the human body, and the most common disease with increased platelet count is primary thrombocytosis.