What is leukocytosis?

It is an increased amount of white blood cells in the blood.

Leukocytosis is often due to an infection somewhere in the body, as white blood cell production increases to help fight it. However, it may also be due to a hereditary cause, allergic reaction, inflammation or cancer.

Leukocytosis is usually divided into 5 main types - dependent on the type of white blood cell that has increased levels.

Neutrophillic Most commonly caused by infections (almost always bacterial), sterile inflammation, tissue necrosis and burns are also possibilities. It is also more common in infants with an extremely low birth weight.

Esinophilia Causes include allergy and drug hypersensitivity, infections and dermatologic (skin) disorders.

Monocytosis Commonly caused by bacterial infections, protozoal and viral infections, malignant tumors and autoimmune diseases. The infections that cause it are often chronic.

Basophilic This variety is rare, but can be caused by Myleoproliferative disease (bone marrow disorders leading to increased cell production).

Hope this helps and let me know if I can do anything else:)