White Blood Cell Count

Also known as: WBC; Leucocyte count; White count

The Test Sample

What is being tested?

The white blood cell (WBC) count indicates the number of white blood cells in a sample of blood. This count provides a clue to the presence of illness. White blood cells are made in the bone marrow and protect the body against infection and aid in the immune response. If an infection develops, white blood cells attack and destroy the bacteria causing the infection.

How is the sample collected for testing?

The blood sample is obtained by a needle placed in a vein in the arm or by a fingerprick or heelprick (for newborns).

NOTE: If undergoing medical tests makes you or someone you care for anxious, embarrassed, or even difficult to manage, you might consider reading one or more of the following articles: Coping with Test Pain, Discomfort, and Anxiety, Tips on Blood Testing, Tips to Help Children through Their Medical Tests, and Tips to Help the Elderly through Their Medical Tests.

Another article, Follow That Sample, provides a glimpse at the collection and processing of a blood sample and throat culture.

If you don't know what a word or a medical term means, try the Mondofacto Online Medical Dictionary .