A white blood cell count (WBC) is a blood test to measure the number of white blood cells (WBCs). It is normally ordered as part of the complete blood count (CBC). In some circumstances, a WBC count may be ordered to monitor recovery from illness. The WBC count detects dangerously low numbers of these cells.
An increased number of white blood cells is called leukocytosis. This can result from bacterial infections, inflammation leukemia, trauma, intense exercise, or stress.
A decreased WBC count is called leukopenia. It can result from many different situations, such as chemotherapy, radiation therapy, or diseases of the immune system.