Low white blood cell counts rarely occur by inherited diseases. A low WBC count generally arises from decreased production of white blood cells due to drugs, vitamin B12 deficiency or infection. The condition can also occur from peripheral destruction due to autoimmune disorders such as rheumatoid arthritis and lupus erythematosis. According to BloodBook.com, the normal white blood cell count ranges from 4,300 to 10,800 cells/µL. MayoClinic.com defines a low white blood cell count in adults as fewer than 3,500 cells/µL.
Infection
According to "Harrison's Principles of Internal Medicine", when a patient's neutrophil count drops to 1,000 cells/µL, or less, the risk for a life-threatening infection increases dramatically. Neutrophils are bacteria-fighting white blood cells. The neutrophil count of acute leukemia patients who have received chemotherapy may drop to zero neutrophils for many days. These patients may develop life-threatening bacterial infections such as Pseudomonas aeruginosa pneumonia. Consequently, broad-spectrum antibiotics are given to prevent bacterial infections until the patient's neutrophils increase to 1,000 cells/µL or higher.
Control of Microbial Flora
A neutrophil count of 500 or less in patients receiving chemotherapy impairs control of the mouth and gut microflora. Painful ulceration of the mouth, or mucositis, appears within 5 to 10 days of drug or radiation treatment and can last several weeks. Approximately 40 percent of patients receiving chemotherapy develop mucositis, according to PatentStorm.us. Ulceration of the mouth puts the patient at risk for invasion by viruses, especially herpes simple virus and anaerobic mouth flora, both of which cause severe mucositis.
Inflammation
A person with a normal white blood cell count can mobilize white blood cells from bone marrow to the site of an infection. The white blood cells surround bacteria, engulf them and limit their spread. When the neutrophil count drops to 200 or less, the body is unable to mount an inflammatory, or disease fighting process, according to "Harrison's Principles of Internal Medicine."
References
- Mayo Clinic: Low White Blood Cell Count
- "Harrison's Principles of Internal Medicine"; Dennis Kasper, M.D.; 2005
- Blood Book: Blood Test Results-Normal Ranges
- Patent Storm: Methods for alleviating mucositis
