Leucocytosis

Leucocytosis is an increase in the number of white blood cells in the blood. It is a common feature of inflammatory reactions, particularly those caused by bacteria. The type of leucocyte increasing in number is dependent on the stimulus type and chronicity; subtypes include:

• neutrophilia
• basophilia
• eosinophilia
• lymphocytosis
• monocytosis

The level of leucocytosis is an insensitive guide to the severity of established infection. Typical values are:

• abscesses: 11-20 x 10⁹ per litre
• peritonitis: >20 x 10⁹ per litre
• septicaemia: up to 100 x 10⁹ per litre - a leukaemic reaction - or conversely, very low levels

Leucocytosis should be contrasted with leucopenia.

Reference

1. Chabot-Richards DS, George TI. Leukocytosis. Int J Lab Hematol. 2014 Jun;36(3):279-88.