Also known as: WBC count, white blood cell count, white cell count
Name: White blood cell count
Related tests: Blood smear, Full blood count
Why is the test done?
When the doctor suspects an active infection or a disease that affects white cell production, and to monitor treatment.
When is it done?
As part of the full blood count (FBC), which may be requested for a wide variety of reasons.
What samples are required?
A blood sample taken from a vein in the arm, by finger-prick (children and adults) or by heel-prick (newborn babies).
What is being analysed?
The white blood cell (WBC) count shows the number of white cells in the blood sample. An abnormal count can be a direct sign of disease. White cells are produced in the bone marrow and protect the body against infection and help with the immune response. If an infection develops, white cells attack and destroy the bacteria, fungi or viruses causing it.
How is the sample collected for testing?
The test is carried out on a blood sample taken with a needle from a vein in the arm, by finger-prick (children and adults) or by heel-prick (newborn babies).
How is it used?
When is it requested?
What does the test result mean?
What else should I know?
How is it used?
Conditions or treatments that weaken the immune system, such as HIV or chemotherapy, reduce the number of white cells. The white blood cell (WBC) count detects dangerously low numbers of these cells.
The WBC count is used to detect an infection or leukaemia. It is also used to monitor the body’s response to various treatments and bone marrow function.
When is it requested?
The WBC count is normally part of a full blood count (FBC), which is ordered for a wide range of reasons. The WBC count may also be ordered to assess recovery after an illness. A count that keeps rising over time or falls below normal indicates that the patient’s condition is getting worse. A count that returns to normal indicates recovery.
What does the test result mean?
A high white cell count is called leucocytosis. It may result from bacterial infection, inflammation, leukaemia, trauma or stress.
A low WBC count is called leucopenia. It may result from various conditions, such as chemotherapy, radiotherapy or immune system diseases.
What else should I know?
Food, physical activity and stress can cause an increase in white cells.
Pregnancy in its final months and childbirth may be associated with an increased WBC count.
Splenectomy may be followed by a mild to moderate increase in white cells. The white cell count normally follows a daily rhythm, being lower in the morning and higher in the evening.
The WBC count is related to age. Newborns and children tend to have higher white cell counts than adults. It is not uncommon for them to develop leucocytosis in response to an infection. Many medicines can cause either an increase or a decrease in the WBC count.
1. Are there different types of WBC?
2. How are abnormal WBC levels treated?
1. Are there different types of WBC?
Yes. There are five main groups: neutrophils, lymphocytes, monocytes, eosinophils and basophils.
2. How are abnormal WBC levels treated?
Treatment depends entirely on the cause. Infections usually cause an increase in white cells and can be treated with antibiotics. Leukaemia requires chemotherapy or other treatments.