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Agranulocytosis, also known as agranulosis or granulopenia, is an acute condition involving a severe and dangerous leukopenia (lowered white blood cell count), most commonly of neutrophils causing a neutropenia in the circulating blood.〔(eMedicine/Stedman Medical Dictionary )〕 It is a severe lack of one major class of infection-fighting white blood cells. People with this condition are at very high risk of serious infections due to their suppressed immune system. In agranulocytosis, the concentration of granulocytes (a major class of white blood cells that includes neutrophils, basophils, and eosinophils) drops below 500 cells/mm³ of blood. ==Classification== The term "agranulocytosis" derives from the Greek: ''a'', meaning without; granulocyte, a particular kind of white blood cell (containing granules in its cytoplasm); and ''osis'', meaning condition (disorder ). Consequently, agranulocytosis is sometimes described as "no granulocytes", but a total absence is not required for diagnosis. However, "-osis" is commonly used in blood disorders to imply cell proliferation (such as in "leukocytosis"), while "-penia" to imply reduced cell numbers (as in "leukopenia"); for these reasons, granulopenia is a more etymologically consistent term, and as such, is sometimes preferred to "agranulocytosis" (which can be misinterpreted as "agranulocyt-osis", meaning proliferation of agranulocytes (i.e. lymphocytes and monocytes). Despite this, "agranulocytosis" remains the most widely used term for the condition. The terms agranulocytosis, granulocytopenia and neutropenia are sometimes used interchangeably. Agranulocytosis implies a more severe deficiency than granulocytopenia. Neutropenia indicates a deficiency of neutrophils (the most common granulocyte cell) only. To be precise, neutropenia is the term normally used to describe absolute neutrophil counts (ANCs) of less than 500 cells per microlitre, whereas agranulocytosis is reserved for cases with ANCs of less than 100 cells per microlitre. The following terms can be used to specify the type of granulocyte referenced: * Inadequate numbers of neutrophils: neutropenia (most common) * Inadequate numbers of eosinophils: eosinopenia (uncommon) * Inadequate numbers of basophils: basopenia (very rare) 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「agranulocytosis」の詳細全文を読む スポンサード リンク
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