What it is:
A white blood cell (WBC) count (sometimes called leukocyte count or white count) may be ordered by a physician as part of a complete blood cell count (CBC). A WBC count is the number of white blood cells per volume of blood, and is reported in either thousands in a microliter or millions in a liter of blood.
What it's used for:
A high WBC count can be an indicator of an infection, inflammation, or allergy. Some conditions may cause a decrease in the WBC count.
Leukocytosis is the presence of an elevated WBC count; leukopenia is a decreased WBC count. Leukocytosis may be caused by several conditions including bacterial infection, inflammation, leukemia, trauma, or stress. Leukopenia may occur as a result of chemotherapy, radiation therapy, or immune system disorders.
How it's done:
A blood sample will be taken, normally from the arm. If several tests are ordered, more than one vial of blood will be taken.
Normal levels:
The normal range for WBC count is 4,300 to 10,800 cells per cubic millimeter (cmm) or 4.3 to 10.8 x 109 cells per liter. A range of 11 to 17 x 109/L may be considered mild to moderate leukocytosis, and a range of 3.0 to 5.0x109/L may be considered mild leukopenia.
