A white blood cell count of 15 to 20 x 10^9/L is considered high and serious based on the value alone, but the exact cause of the disease should also be considered. When the white blood cell count is greater than 10×10^9/L, it is considered elevated, and a variety of etiologies can lead to high white blood cell counts, commonly such as acute bacterial infections, severe tissue trauma, acute hemorrhage, acute poisoning, leukemia, and so on. In some acute bacterial infections, a white blood cell count of 15-20 x 10^9/L indicates uncontrolled infection and more serious illness. Severe tissue trauma and acute hemorrhage can lead to massive destruction of blood cells, a rise in white blood cell reactivity, and a more severe condition. Some acute poisonings such as diabetic ketoacidosis, uremia, and snake envenomation result in a white blood cell count of 15 to 20 x 10^9/L, which also represents a more severe condition. In some patients with acute leukemia, the white blood cell count can be as high as 100 x 10^9/L, which is called leukocytosis and is a very serious condition. When the count is 15-20×10^9/L, it is not possible to conclude the severity of the condition, and it is necessary to take into account specific clinical symptoms and other laboratory results. When the white blood cell count is high, it is recommended to consult a doctor for a clear diagnosis and standardized treatment under the guidance of a professional doctor.