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Related to neutrophilic leukocytosis: neutrophilia, Neutrophils




Leukocytosis is a condition characterized by an elevated number of white cells in the blood.


Leukocytosis is a condition that affects all types of white blood cells. Other illnesses, such as neutrophilia, lymphocytosis, and granulocytosis, target specific types of white blood cells. Normal white blood cell counts are 4,300-10,800 white blood cells per microliter. Leukocyte or white blood cell levels are considered elevated when they are between 15,000-20,000 per microliter. The increased number of leukocytes can occur abnormally as a result of an infection, cancer, or drug intake; however, leukocytosis can occur normally after eating a large meal or experiencing stress.

Causes and symptoms

Leukemias can cause white blood cell counts to increase to as much as 100,000. Each kind of white cell can produce a leukemia. Apart from leukemias, nearly all leukocytosis is due to one type of white blood cell, the polymorphonuclear leukocyte (PMN). These conditions are more accurately referred to as neutrophilia.
The most common and important cause of neutrophilia is infection, and most infections cause neutrophilia. The degree of elevation often indicates the severity of the infection. Tissue damage from other causes raises the white count for similar reasons. Burns, infarction (cutting off the blood supply to a region of the body so that it dies), crush injuries, inflammatory diseases, poisonings, and severe diseases, like kidney failure and diabetic ketoacidosis, all cause neutrophilia.
Counts almost as high occur in leukemoid (leukemia-like) reactions caused by infection and non-infectious inflammation.
Drugs can also cause leukocytosis. Cortisone-like drugs (prednisone), lithium, and NSAIDs are the most common offenders.
Non-specific stresses also cause white blood cells to increase in the blood. Extensive testing of medical students reveals that neutrophilia accompanies every examination. Vigorous exercise and intense excitement also cause elevated white blood cell counts.


A complete blood count (CBC) is one of the first tests obtained in any medical setting. More than 11,000 white cells in a cubic millimeter of blood is considered high. Bone marrow biopsy may help clarify the cause.


Relieving the underlying cause returns the count to normal.

Key terms

Biopsy — Surgical removal of tissue for examination.
Inflammation — Heat, swelling, redness, and pain caused by tissue injury.
Ketoacidosis — A severe stage of diabetes where acids and ketones accumulate in the body.
NSAID — Non-steroidal anti-inflammatory drug such as ibuprofen.


By treating the underlying condition, white blood cell counts usually return to normal



Holland, Steven M., and John I. Gallin. "Disorders of Granulocytes and Monocytes." In Harrison's Principles of Internal Medicine, edited by Anthony S. Fauci, et al. New York: McGraw-Hill, 1997.


a transient increase in the number of leukocytes in the blood, due to various causes.
basophilic leukocytosis basophilia (def. 1).
eosinophilic leukocytosis eosinophilia (def. 1).
mononuclear leukocytosis mononucleosis.
neutrophilic leukocytosis neutrophilia.
pathologic leukocytosis that due to some morbid condition, such as infection or trauma.
physiologic leukocytosis that caused by nonpathologic factors such as strenuous exercise.


An abnormally large number of leukocytes, as observed in acute infections, inflammation, hemorrhage, and other conditions. A white blood cell count of 10,000/mm3 (or more) usually indicates leukocytosis Most examples of leukocytosis represent a disproportionate increase in the number of cells in the neutrophilic series, and the term is frequently used synonymously with the designation neutrophilia. Leukocytosis of 15,000-25,000/mm3 is frequently observed in various pathologic conditions, and values as high as 40,000 are not unusual; occasionally, as in some examples of leukemoid reactions, white blood cell counts may range up to 100,000/mm3.
[leukocyte + G. -osis, condition]


/leu·ko·cy·to·sis/ (-si-to´sis) a transient increase in the number of leukocytes in the blood, due to various causes.
basophilic leukocytosis  basophilia (1).
eosinophilic leukocytosis  eosinophilia.
mononuclear leukocytosis  mononucleosis.
neutrophilic leukocytosis  neutrophilia.
pathologic leukocytosis  that due to some morbid condition, such as infection or trauma.
physiologic leukocytosis  that due to a nonpathologic condition such as strenuous exercise.




n. pl. leukocyto·ses (-sēz)
An abnormally large increase in the number of white blood cells in the blood, often occurring during an acute infection or inflammation.

leu′ko·cy·tot′ic (-tŏt′ĭk) adj.


Etymology: Gk, leukos + kytos, cell, osis, condition
an abnormally elevated total peripheral white blood cell count, often associated with bacterial infection. Extreme elevations may be associated with leukemia. Kinds of leukocytosis include basophilia, eosinophilia, and neutrophilia. Also spelled leucocytosis. Compare leukemia, leukemoid reaction, leukopenia. See also leukocyte.


↑ in WBCs–WBC count > 11 x 109/L–US: 11,000/mm3, benign or malignant. See Reactive leukocytosis, WBC. Cf Leukemia, Leukopenia.
Physiologic Follows nonspecific immune stimulation, eg intense exercise; it may be idiopathic or hereditary, neonatal, induced by heat or solar irradiation, diurnal, ↑ in afternoon, related to stress, eg pain, nausea, vomiting, anxiety, womanhood–↑ during ovulation and near term, ↑ during labor, ether anesthesia, ↑ adrenalin, convulsions, paroxysmal tachycardia, pain, nausea, vomiting, anoxia, exercise, convulsions
Pathologic May be due to infections, often bacterial, inflammation, severe burns, post-operative, MI, strangulated hernias, intestinal obstruction, gouty attacks, acute glomerulonephritis, serum sickness, rheumatic fever, immune disorders and connective tissue diseases, metabolism–ketoacidosis, uremia, eclampsia, heavy metals–lead, mercury, petrochemicals–benzene, turpentine, drugs–phenacetin, digitalis, black widow spider venom, endotoxin or toxoid injection, Jarisch-Herxheimer reaction, hemorrhage–often into cranial cavity, serosal surfaces–pleural pericardium and peritoneum or acute hemolysis, malignancy–GI tract or hematopoietic, and Cushing syndrome


An actual increase in the total number of leukocytes in the blood, as distinguished from a relative increase (e.g., in dehydration).
Synonym(s): leucocytosis.
[leukocyte + G. -osis, condition]


abnormally high levels of leukocytes in circulating blood; characteristic of infections
  • eosinic leukocytosis; eosinophilia characteristic of parasitic infections

  • relative leukoytosis increase in proportion of one type of leukocyte within circulating blood but without an overall increase in total number of circulating leukocytes


An abnormally large number of leukocytes, as observed in acute infections, inflammation, hemorrhage, and other conditions.
Synonym(s): leucocytosis.
[leukocyte + G. -osis, condition]

leukocytosis (loo´kōsītō´sis),

n an increase in the normal number of white blood cells; may be a defensive reaction, as in inflammation, or may result from a disturbance in white blood cell formation, as in leukemia. Various limits are given; e.g., leukocytosis in the adult is indicated when there are more than 10,000 white blood cells per cubic millimeter. See also eosinophilia; lymphocytosis; neutrophilia; monocytosis.


a transient increase in the number of leukocytes in the blood, due to various causes.

basophilic leukocytosis
see basophilia (2).
eosinophilic leukocytosis
see eosinophilia (2).
leukocytosis-inducing factor
a factor which causes an increase in release of immature neutrophils into the circulation; an increased level of the factor in the circulation caused by endotoxin; called also neutrophil-releasing activity.
mononuclear leukocytosis
pathological leukocytosis
that due to some morbid reaction, e.g. infection or trauma.
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histolytica cases, it was surprising that 50% or more of these cases had leukocytosis for age, neutrophilic leukocytosis for age, and positive CRP which were significantly higher in E.
Clinical laboratory evaluation showed the following: neutrophilic leukocytosis, hemoglobin 10.
Initial hemogram showed the neutrophilic leukocytosis (white cell count 12700/cmm, 90% neutrophil).
Laboratory studies showed a neutrophilic leukocytosis and elevated sedimentation rate in 24 and 30 patients respectively.