Normal leukocytes are 4000-10000/L, and a routine blood leukocyte count of 19000/L is significantly elevated. First, the most common in the clinic is bacterial infection: respiratory, intestinal, urinary, abdominal and other parts of the organ infections can cause increased leukocytes, such as pneumonia, pancreatitis, acute cholecystitis, acute gastroenteritis, purulent cholangitis, pyelonephritis, etc.. Further improvement of the relevant examination should be carried out after active anti-infection treatment. Second, leukemia may, if it is acute leukemia, the white blood cells may be higher, but there is still the possibility of this disease, necessary is the need for further examination. In summary, for leukocytes 19000 / L, the first choice to consider the above two cases, according to the patient’s symptoms and test results to clarify the diagnosis.