leukocytosis

An abnormally large number of leukocytes, as observed in acute infections, inflammation, hemorrhage, and other conditions. A white blood cell count of 10,000 or more per mm³ usually indicates l. Most examples of l. represent a disproportionate increase in the number of cells in the neutrophilic series, and the term is frequently used synonymously with the designation neutrophilia. L. 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 reaction s, white blood cell counts may range up to 100,000/mm³. [leukocyte + G. -osis, condition]

- absolute l. an actual increase in the total number of leukocytes in the circulating blood, as distinguished from a relative increase (such as that observed in dehydration).

- agonal l. SYN: terminal l..

- basophilic l. the presence of an abnormally large number of basophilic granulocytes in the blood. SYN: basocytosis.

- digestive l. l. occurring normally after ingestion of food.

- distribution l. an abnormally large proportion of one or more types of leukocytes.

- emotional l. an abnormally high white blood cell count that is thought to be related only to an emotional disturbance.

- eosinophilic l. a form of relative l. in which the greatest proportionate increase is in the eosinophils. SYN: eosinophilia.

- lymphocytic l. SYN: lymphocytosis.

- monocytic l. SYN: monocytosis.

- neutrophilic l. SYN: neutrophilia.

- l. of the newborn an apparently “physiologic” l. usually observed in newborn infants, in whom the white blood cell counts are usually greater than 10,000/mm³, and sometimes range to 45,000/mm³, resulting chiefly from increased numbers of neutrophils (especially single and bilobed forms). On the third or fourth day of life, the count generally decreases rapidly, and then fluctuates for several days; beginning about the fourth week of life, a relative lymphocytosis is observed, and this normally continues for a few years.

- physiologic l. any form of l. that is associated with apparently normal situations and that is not directly related to a pathologic condition; e.g., the temporary increase in the total number of white blood cells that may occur during a single day, or from day to day, as well as in the newborn period, during childhood, after strenuous exercise, during attacks of paroxysmal tachycardia, and in association with various other situations.

- relative l. an increased proportion of one or more types of leukocytes in the circulating blood, without an actual increase in the total number of white blood cells.

- terminal l. one that occurs in a person just prior to death, especially in one who has a “slow death.” SYN: agonal l..

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leu·ko·cy·to·sis or chiefly Brit leu·co·cy·to·sis .lü-kə-sī-'tō-səs, -kə-sə- n, pl -to·ses -.sēz an increase in the number of white blood cells in the circulating blood that occurs normally (as after meals) or abnormally (as in some infections)

leu·ko·cy·tot·ic or chiefly Brit leu·co·cy·tot·ic -'tät-ik adj

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leu·ko·cy·to·sis (loo″ko-si-toґsis) a transient increase in the number of leukocytes in the blood; seen normally with strenuous exercise and pathologically accompanying hemorrhage, fever, infection, or inflammation. Cf. hyperleukocytosis.