Elevated white blood cells are not necessarily leukemia. Elevated white blood cells may be caused by leukemia, or due to physiological phenomena, inflammation and other reasons. 1. Leukemia: the causative factors of leukemia have not been completely clarified. The pathophysiological change of leukemia is that under the action of certain pathogenic factors, leukemia cells proliferate uncontrollably, differentiation is blocked and apoptosis is inhibited. 2. Physiological phenomenon: common causes include labor or pregnancy, strenuous exercise, prolonged exposure to cold environment, full stomach and so on. Due to the stimulation of excessive leukocytes into the peripheral blood, elevated leukocytes can be found in routine blood tests. 3. Inflammation: Infection is one of the most common pathological causes of elevated white blood cells. When the organism is infected by pathogenic microorganisms such as bacteria, fungi and other pathogenic microorganisms and local or systemic inflammation occurs, the number of leukocytes can have a significant increase. It is recommended that patients with elevated white blood cells should identify the cause of the disease in a timely manner, and then follow the doctor’s instructions for treatment to avoid delaying the condition.