The blood test is very quick, usually between half an hour and two hours, and the main purpose of the blood test is to observe whether an infection has occurred. In the case of bacterial infections, there is usually a significant increase in white blood cells or neutrophils. In the case of viral infections, there will be a mild increase or decrease in white blood cells and a mild increase in eosinophils. In the case of parasitic infections or allergies, eosinophils may be elevated. The main purpose of routine blood tests is to observe whether there is anemia, such as a decrease in hemoglobin, which may be caused by iron deficiency anemia or other causes. Therefore, blood test is a very important test to check the underlying pathology, often everyone needs to be checked, and the results of the test need to choose the appropriate treatment plan for treatment, the effect is better.