These instruments provide the total white blood cell count, expressed as cells per microliter of blood, as well as the proportion of each of the five major types of white blood cells. The total white blood cell count normally ranges between 4,000 and 10,000 cells per microliter. Too few or too many white blood cells indicates a disorder. Leukopenia, a decrease in the number of white blood cells to fewer than 4,000 per microliter, makes a person more susceptible to infections. Most white blood cell disorders involve neutrophils, lymphocytes, monocytes, and eosinophils.
Disorders involving basophils are very rare.
Neutropenia Neutropenia is an abnormally low number of neutrophils in the blood. Neutrophils are the body's primary cellular defense system against bacteria and fungi. They also help heal wounds and ingest foreign debris, such as embedded splinters. Neutrophils mature in the bone marrow in about 2 weeks. After entering the bloodstream, they circulate for about 6 hours, searching for infective organisms and other intruders.