Leukocytosis, Leukopenia, and Other Changes of the Myeloid Series

Most changes in the white blood cell count are reactive and due to an increase or decrease of cells of the myeloid series. Normal blood count values are presented in Appendix 3, p. 347. By definition, a leukocytosis is present if leukocytes are increased to more than 10,000/μL. In leukopenia leukocytes are below 4000/μL. Infants and small children have slightly different normal values. A neutropenia is present if granulocytes are below 2000/μL, agranulocytosis if granulocytes are below 500/μL. Granulocytes are considered to be increased in number if they are >8000/μL. In leukemoid reactions, leukocyte counts greater than 30,000/μL are found. A left shift in the differential count means that the number of band forms (and other precursors like metamyelocytes) is increased to more than 5%. In a pathological left shift more immature precursors like promyelocytes can be seen in the peripheral blood; this is almost always a sign of a hematological disorder. These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.