White Blood Cells - Overview
White blood cells are the cells of the immune system and their primary role is to fight against infections and foreign bodies which enter the human body. There are the several different types of leukocytes. All of them originate from one multipotent cell in the bone marrow called hematopoietic stem cell. All the leukocytes can be classified into granulocytes and agranulocytes. Granulocytes include neutrophils, basophils and eosinophils while agranulocytes include lymphocytes, monocythes and macrophages.
White blood cell count is a diagnostic method which provides with information on how many leukocytes there are in the human body. Apart from obtaining the relevant data regarding the total amount of white blood cells this test allows a doctor to have perfect insight in the number (percentage) of all the types of white blood cells. This is essential since any disturbance of these cells may point to the presence of certain illnesses.
Why is White Blood Cell Count Ordered
This test is performed during general examination and also in special cases when the doctor investigates a variety of illnesses.
Elevated white blood cell count is typical for infections of any kind, allergies, systemic illnesses, inflammation, injuries and leukemia. On the other hand, low white blood cell count occurs in certain viral infections, immunodeficiency and in bone marrow failure. Low white blood cell count is also a side effect of certain medications such as chemotherapeutics.
White blood cell count is essential in setting of the diagnosis of many illnesses and it also provides with information related to the efficiency of treatment. Differential differences between the types of leukocytes gives information related to which type is particularly affected by the illness. For example, in infective mononucleosis the typical result will point to the elevation of white blood count with an absolute increase in lymphocytes. Apart from the previously mentioned lymphocytes also feature with atypical appearance.
Interpretation of the Results
While interpreting white blood cell count it is crucial to check whether the patient takes medications which may interfere in optimal number of leukocytes. Any change in number of leukocytes requires further examination and tests which will help in setting of the definitive diagnosis and the underlying condition which has affected white blood count.
Normal results basically vary with age. The highest number of white blood cells is recorded in children. This number decreases until adulthood and the decrease is most evident in the lymphocyte population. Normal values of leukocytes in adults are:
WBC count: 4.500 - 11.000/µL
polymorphonuclear neutrophils: 1.800 - 7.800 /µL (50-70%)
band neutrophils: 0 - 700 /µL (0-10%)
lymphocytes: 1.000-4.800 /µL (15-45%)
monocytes: 0-800/µL (0-10%)
eosinophils: 0-450/µL (0-6%)
basophils: 0-200/µL (0-2%)