Leukocytosis
This is an increase in the leukocyte count (normal range is 4-8×109 leukocytes/l) in the blood (more than 11×109/l). Usually, this is a general body response during infection or inflammation. Physical or emotional stress can also increase the number of leukocytes. When there are very high levels of leukocytes, abnormal counts of erythrocytes or thrombocytes, weight loss, bleeding, enlarged internal organs, bone marrow damage can occur – leukemia or myeloproliferative syndrome. The causes of leukocytosis are grouped based on the bone marrow response: whether the bone marrow is healthy or there are bone marrow abnormalities (blood disorder). A normal bone marrow response occurs when there is: infection; inflammation: tissue necrosis, infarction, burns, arthritis; stress: fatigue, seizures, anesthesia; drug effects: corticosteroids, beta agonists; trauma; splenectomy; hemolytic anemia; leukemoid reaction, caused by cancer intoxication. During a normal bone marrow response, when the leukocyte count in peripheral blood increases, mature neutrophils and less mature myeloid cells – metamyelocytes predominate. They gather in the area of damage, which is called a “shift to the left.” Stress-induced leukocytosis disappears within a few hours of removing the causative factor. Splenectomy causes temporary leukocytosis, which lasts for several weeks or months. In malignant blood diseases, there is leukocytosis, sometimes thrombocytosis, because tumor cells multiply and increase in the bone marrow and blood. An increased number of neutrophils is the most common form of leukocytosis, but there can also be eosinophilia (more than 0.44×109/l), basophilia (more than 0.1×109/l), lymphocytosis (more than 3.5×109/l), monocytosis (more than 0.8×109/l). Leukocytosis indicates bone marrow damage (blood cancer): acute and chronic leukemias and myeloproliferative syndrome. Acute hemoblastoses develop from young stem cells and predominate, while chronic hemoblastoses involve cells of various maturation levels.
Source | Glossary of Most Commonly Used Biomedical Terms and Concepts | Lithuanian University of Health Sciences | Academician Professor Antanas Praškevičius, Professor Laima Ivanovienė