9 6 However, even in very old individuals, red cell production and erythropoietin synthesis are usually adequate to keep hemoglobin levels within a reasonable range unless certain co-morbidities that lead to insufficient production of red cells have been acquired. As a result, erythropoietin synthesis and red cell production may decline. In the elderly, the bone marrow and other organs undergo aging. 5 2 However, in some pathological conditions this regulatory network is overwhelmed or is not functional, resulting in polycythemia or anemia. 5 2 This regulatory network can adjust itself to physiological requirements such as the oxygen concentration (altitude) or pregnancy as well as to pathological conditions such as blood loss. A complex network of oxygen sensors, cytokines, such as erythropoietin, and other factors, including regulators of iron metabolism, are involved in the control of steady-state and stress-induced erythropoiesis, thereby ensuring appropriate oxygen supply to the peripheral tissues. 1 Depending on demand, red cell production can be adjusted and upregulated substantially. In healthy adults, about 200×10 red cells are produced per day in the bone marrow and are released into the peripheral blood. The use and usefulness of established and novel erythropoiesis-stimulating agents for various indications, including myelodysplastic syndromes and other neoplasms, are also discussed.Įrythropoiesis is one of the important physiological supply functions of the bone marrow. The outcomes of this workshop are summarized in this review, which includes a discussion of new diagnostic and prognostic markers, the updated WHO classification, and an overview of new drugs used to stimulate or to interfere with erythropoiesis in various neoplastic and reactive conditions. In order to discuss new markers, targets and novel therapeutic approaches in erythroid disorders and the related pathologies, a workshop was organized in Vienna in April 2017. Although several mechanisms underlying normal and abnormal erythropoiesis and the pathogenesis of related disorders have been deciphered in recent years, little is known about specific markers and targets through which prognosis and therapy could be improved in anemic or polycythemic patients. Rarely, clonal expansion of immature erythroid blasts results in a clinical picture resembling erythroid leukemia. Clonal expansion of erythroid cells in the bone marrow may result in peripheral erythrocytosis and polycythemia but can also result in anemia when clonal cells are dysplastic and have a maturation arrest that leads to apoptosis and hinders migration, a constellation typically seen in the myelodysplastic syndromes. The etiologies of anemia are complex and include reactive as well as neoplastic conditions. Pathological erythropoiesis with consequent anemia is a leading cause of symptomatic morbidity in internal medicine.
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