Your body produces white blood cells (leukocytes), which help fight bacterial infections, viruses and fungi. There are several types of white blood cells, each with a different disease-fighting activity.

A white blood cell disorder can mean that your child has too few or too many white blood cells of a certain type, which can cause, or be caused by, serious health problems. Types of white blood cell disorders include low white blood cell count (leukopenia), high white blood cell count (leukocytosis), neutropenia, lymphocytopenia, monocyte disorders and eosinophilia, among others.


There are many types of white blood cell disorders, such as:

  • Low white blood cell count. Low white blood cell count, or leukopenia, means having too few disease-fighting cells (leukocytes) circulating in the blood. A long-term low white blood cell count increases risk of infections and may be caused by a number of different diseases and conditions.
  • High white blood cell count. High white blood cell count, or leukocytosis, means having too many leukocytes circulating in the blood. A number of different diseases and conditions may cause a long-term high white blood cell count.
  • Neutropenia. Neutropenia is a low number of neutrophils, a kind of white blood cell that fights infections of fungi and bacteria. Neutropenia can be caused by a problem in the bone marrow or by a condition that prematurely destroys cells in the bloodstream. In addition, certain medications and other diseases or conditions can cause neutropenia.
  • Lymphocytopenia. Lymphocytopenia (lim-fo-si-toe-PE-ne-uh) is a decrease in lymphocytes, the type of white blood cell that, among other tasks, protects your body from viral infections. It can result from an inherited syndrome, be associated with certain diseases, or be a side effect from medications or other treatments.
  • Monocyte disorders. Monocytes help get rid of dead or damaged tissue and regulate your body's immune response. Infections, cancer, autoimmune diseases and other conditions can cause an increased number of monocytes. A decreased number can be the result of toxins, chemotherapy and other causes.
  • Eosinophilia. Eosinophilia (e-o-sin-o-PHIL-e-uh) is a higher than normal number of eosinophil cells, a type of disease-fighting white blood cell. Eosinophilia can be caused by a variety of conditions, diseases and factors, most commonly by an allergic reaction or a parasite infection.
Nov. 20, 2012