White blood cells, also referred to as WBCs or leukocytes, protect the body from potentially harmful foreign particles. They arise from stem cells within the bone marrow and mature into neutrophils, eosinophils, basophils, lymphocytes and monocytes. The main cause of leukocytosis, which is a WBC count greater than 11x10^9 per L, is normal bone marrow response or abnormal bone marrow. Healthy bone marrow will increase WBC production in cases of infection, inflammation, anemia, malignancy, or physical and emotional stress. Primary bone marrow disorders, including leukemias and myeloproliferative disorders, have a WBC count greater than 30x10^9 per L, according to American Family Physician.
Infection
A pathogen, weakened immune system, lack of immunizations, invasion by bacteria, viruses, parasites, fungi or a prion, which is a protein-based pathogen, will result in infection. Such infections can be local, such as a tooth abscess, or systemic, such as sepsis, invading the blood stream and multiple organs. Treatments usually involve antimicrobial medications or surgical debridement of infected tissues. There are no effective treatments for prions, certain viruses and bacteria, such as antibiotic resistant strains of MRSA, says the U.S. Centers for Disease Control.
Inflammation
Inflammation is a response to injury via increased blood flow and WBC count. It is characterized by redness, pain, heat, swelling, or flu-like symptoms. Inflammation is an integral component of autoimmune disorders, asthma, allergic reactions and tissue trauma, including burns and infarction. Treatments for inflammation vary from anti-inflammatory drugs to recombinant DNA and monoclonal antibodies used for treatment of autoimmune disorders, reports American Family Physician.
Stress
Physical stress, inclua ding heat stroke, seizures or surgery, and psychiatric disorders such as bipolar disorder, depression or anxiety, cause mild to moderate increases in WBC count. Smoking has been associated with 30 percent increase in WBC count, even after cessation, according to the American Journal of Clinical Pathology. Leukocytosis, as a result of obesity or pregnancy, is normal.
Anemia and Malignancy
Hemolytic, sickle cell and iron-deficiency anemias are characterized by leukocytosis in conjunction with increased red blood cell production. Malignant tumors, such as lymphomas or lung cancer, may stimulate bone marrow to produce excess WBCs. Leukomoid reaction, which is a WBC count over 50x10^9 per L, is leukocytosis associated with diseases outside the bone marrow such as inflammation or infection, and less frequently, malignancy, reports American Family Physician.
Primary Bone Marrow Disorders
Acute leukemias, both lymphocytic and non-lymphocytic, arise from stem cell abnormalities and require immediate treatment. A WBC count over 100x10^9 per L is associated with life-threatening bleeding, infection, and infarction, which is tissue death caused by lack of oxygen and blood supply . Chronic leukemias, both lymphocytic and myelogenous, are often an incidental finding with abnormal and malignant proliferation of differentiated WBCs. If asymptomatic, chronic leukemias do not require treatment. However, chronic myelogenous leukemia eventually evolves into a critically acute state.
Myeloproliferative disorders are a group of bone marrow disorders with abnormal levels of WBCs, red blood cells and platelets. They exhibit varying degrees of leukocytosis, and include polycythemia vera, or elevated red blood cell count; chronic myelogenous leukemia; myelofibrosis, or fibrosed bone marrow; and essential thrombocythemia, an elevated platelet count. Polycythemia vera and essential thrombocythemia are usually asymptomatic, and do not require immediate therapy. Polycythemia vera patients are at risk for strokes and infarcts, while thrombocytopenic patients risk thrombosis and hemorrhage. Myelofibrosis is often an incidental finding in patients over age 50, with enlarged spleen and fatigue. It eventually transforms into aggressive acute leukemia requiring emergent attention.
References
- "American Family Physician"; Leukocytosis: Basics of clinical assessment; Abramson, N., et al. ; November 2000
- CDC: Antimicrobial Resistance in Healthcare Settings. March 2010.
- "Epilepsia". Peripheral WBC count and serum prolactin level in various seizure types and nonepileptic events; Shah, A. K., et al. C. ; November 2001
- "Progress in Neuro-Psychopharmacology and Biological Psychiatry". Fever and leukocytosis: Physical manifestations of bipolar affective disorder?; Kronfol, Z., et al.; 1988
- American "Journal of Clinical Pathology". Smoking, alcohol consumption, and leukocyte counts; Parry, H., et al.; January 1997
