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What causes leukocytosis, an abnormally high white blood cell count?
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white blood cell
Blood is made up of multiple components, including red blood cells, white blood cells, platelets, and water-rich plasma.
Leukocytosis is defined as an abnormally high number of white blood cells (leukocytes) in the blood circulation, typically exceeding 10,000 cells per cubic millimetre. This condition is usually caused by an increase in the number of granulocytes, particularly [neutrophils].123
The primary causes of leukocytosis include:
- Infection: This is the most common cause, often involving pyogenic organisms that trigger the bone marrow to increase production of white cells.12
- Physiological Stress: Temporary increases can occur due to strenuous exercise, intense physical exertion, convulsions, acute emotional reactions, or [pain].143
- Medical and Biological States: It may occur during pregnancy, labour, or following the administration of [epinephrine].13
- Environmental and Pathological Factors: Causes include lack of oxygen (such as during adaptation to high altitude), allergic reactions, parasitic infestations, and intoxications (metabolic or chemical).12
- Chronic Disease: Conditions such as leukemia are also associated with significantly elevated white blood cell counts.13