White blood cells [wbc]

White blood cells fight infection in the body. Their level is often raised in the presence of infection, but they may become low with some infections, as well as with some drugs. White blood cells consist of different types, but the most important ones for fighting common infections are called neutrophils. Normal range = 4-11 thousand million/ml).

below 4
Very low counts (especially neutrophil counts; or total counts below 2 or 3) indicate serious risk of infection, or sign of severe infection. Can be caused by drugs or blood diseases.
over 11
Often suggests infection though there are other causes, including treatment with high doses of steroids. Rarely, very high counts may occur in blood diseases.

This result generally comes back as part of a 'full blood count', FBC (or complete blood count, CBC).

Other white blood cell types include lymphocytes, which are important for fighting virus infections, and eosinophils, which are increased in allergy and asthma. Many blood cell counters now automatically give the numbers of the different types of wbc, as well as the total count.

More info about White blood cell counts from Lab Tests Online

This page created 6th December 2004, last modified Feb 16, 2015, on the PatientView website