Leukocytes 20×10^9/L indicates the presence of certain diseases in the organism such as infections, severe tissue injuries, hematologic disorders. 1. Acute infections: Staphylococcus aureus, Streptococcus pneumoniae and other purulent cocci infections. 2. Serious tissue injury: acute myocardial infarction, severe intravascular hemolysis, extensive burns, etc. The total number of white blood cells is elevated. 3. Acute hemorrhage: especially internal hemorrhage leukocytes up to 20×10^9/L. 4. hematologic diseases, malignant solid tumors: leukemia, myeloproliferative neoplasms, hepatocellular carcinoma, gastric carcinoma and so on. When there are white blood cells greater than 20×10^9/L, one should immediately consult a doctor to clarify the cause of the disease and take timely measures to improve the quality of life.