Routine blood test can help to find out hematologic diseases, viral infections, bacterial infections and so on. 1. Blood system diseases: routine blood test can check whether the number and proportion of white blood cells, red blood cells and platelets are normal to know whether there are leukemia, anemia, idiopathic thrombocytopenic purpura and other diseases. 2. Viral infection: through the percentage of lymphocytes in routine blood test to determine whether the organism has viral infection. 3. Bacterial infections: determine whether there are bacterial infections through the total number of white blood cells and neutrophil counts in routine blood tests, such as high white blood cells to consider bacterial infections. The routine blood test is widely used in clinical practice, and can be used as a preliminary screening for various related diseases, but the diagnosis of the disease needs to be combined with the patient’s other examination reports and clinical manifestations, so it is recommended that the patient go to a regular hospital for examination.