TY - CHAP M1 - Book, Section TI - Polyclonal Erythrocytoses (Primary and Secondary) A1 - Lichtman, Marshall A. A1 - Kaushansky, Kenneth A1 - Prchal, Josef T. A1 - Levi, Marcel M. A1 - Burns, Linda J. A1 - Linch, David C. Y1 - 2022 N1 - T2 - Williams Manual of Hematology, 10e AB - Erythrocytosis, also referred to as polycythemia, is characterized by an increased red cell mass. There is no consensus on terminology as it relates to the choice of erythrocytosis or polycythemia (ie, primary familial and congenital polycythemia but postrenal transplantation erythrocytosis). Herein, the term polycythemia will only be used for polycythemia vera, an acquired clonal disorder caused by somatic mutations (Chap. 42), and polyclonal erythrocytosis will be used for all other states discussed in this chapter.An erythrocytosis can be primary or secondary and can be inherited or acquired.Classification of polycythemic disorders appears in Table 2–2 in Chap. 2.A primary polycythemia/erythrocytosis is caused by somatic or germline mutations within hematopoietic stem cells or erythroid progenitors that result in an augmented response to erythropoietin (EPO). This response is not a compensation for hypoxia and thus is inappropriate for tissue needs.A secondary erythrocytosis is caused by either an appropriate (compensatory) or inappropriate increase in the red cell mass and, in most instances, results from an augmented level of EPO. SN - PB - McGraw-Hill Education CY - New York, NY Y2 - 2024/11/08 UR - hemonc.mhmedical.com/content.aspx?aid=1189333694 ER -