There are many causes of leukocytosis that are not harmful in themselves; it is the degree of leukocytosis and the true etiology of the increase that can cause serious harm.
White blood cells are a routine and important indicator in clinical testing. When the body is attacked by a virus or inflammation, there are more white blood cells, which is a stress response of the body. We can get a good picture of the health of the body by measuring the type and count of white blood cells in the blood.
A normal adult has a total white blood cell count of (4.0-10.0) x 10^9/L. If the count is high, it may be due to physiological factors, such as strenuous exercise, physical effort, or even overeating, stress, or starvation that can cause changes in the white blood cell count.
But if the change is significant, it may also be pathological, and this is where the causative factor needs to be clarified in conjunction with the leukocyte classification. For example, when neutrophils are found to be high, it means that the body is suffering from inflammation, meaning that there may be damage in the body such as bleeding, blood clots or tumors. If there is an increase in eosinophils, this indicates that there is a parasitic or bacterial infection in the body. And when there is an increase in lymphocytes, this indicates that there is a viral or bacterial infection, or that antibodies are being produced by the immunity produced in the body at a later stage of the infection. However, this needs to be judged together with the actual condition of the patient and in conjunction with other tests. In severe cases, it may be a malignancy of the hematopoietic system, that is, having leukemia resulting in a high number of white blood cells.