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BJU International Dec 2003
Topics: Aged; Erythrocyte Indices; Finasteride; Hematocrit; Hemoglobins; Humans; Male; Polycythemia; Prostatic Hyperplasia; Urological Agents
PubMed: 19127639
DOI: 10.1111/j.1464-410x.2003.04162.x -
Advances in Experimental Medicine and... 2007Hemoglobin, the sole carrier of oxygen to tissues, accounts for most cytoplasmic protein of the erythrocyte, an enucleate cell lacking protein synthesizing machinery and... (Review)
Review
Hemoglobin, the sole carrier of oxygen to tissues, accounts for most cytoplasmic protein of the erythrocyte, an enucleate cell lacking protein synthesizing machinery and with limited energy metabolism. While a number of genetic mechanisms can result in decreased hemoglobin concentration in the blood, this review concentrates on those that lead to increased hemoglobin mass, i.e. polycythemia or erythrocytosis. Polycythemia may be due to (a) mutations of the enzyme synthesizing 2, 3 BPG, a metabolic intermediate which regulates hemoglobin-oxygen affinity and thus oxygen delivery, (b) mutation of the alpha or beta globin genes that increase hemoglobin-oxygen affinity and thus decrease oxygen delivery, and (c) mutations of the erythropoietin receptor gene or genes regulating erythropoietin production that lead to increased production of erythrocytes. Primary polycythemias are caused by inherited or acquired somatic mutations affecting the hematopoietic progenitors. In contrast, in secondary polycythemia normal progenitors are activated by external factors present in increased concentration, most commonly erythropoietin. Some hypoxia sensing disorders blur the distinction between primary and secondary polycythemias and may deserve their own category. Most polycythemias are acquired, but both primary and secondary polycythemias may be inherited. In this review we will discuss the genetic heterogeneity of individual responses to hypoxia, and the current understanding of inherited primary and secondary polycythemias.
Topics: Erythropoietin; Genetic Variation; Hemoglobins; Humans; Hypoxia; Mutation; Polycythemia
PubMed: 18269198
DOI: 10.1007/978-0-387-75434-5_15 -
Acta Medica Croatica : Casopis... 2011Post-transplant erythrocytosis is defined as an increase in hematocrit above 55%. It occurs in 10%-15% of renal transplant recipients, most commonly from 8 to 24 months... (Review)
Review
Post-transplant erythrocytosis is defined as an increase in hematocrit above 55%. It occurs in 10%-15% of renal transplant recipients, most commonly from 8 to 24 months after transplantation. Twenty-five percent of patients experience spontaneous remission within 2 years, while 75% develop symptoms and signs of hyperviscosity (headache, hypertension, plethora). The etiology is multifactorial and includes erythropoietin, renin-angiotensin system (RAS) and IGF-1 as the main factors. RAS inhibition with either ACE inhibitors or angiotensin receptor blockers is efficient therapy which decreases hematocrit in 90% of patients within 2 to 6 weeks, thus decreasing the incidence of fatal complications (like pulmonary embolism and stroke).
Topics: Humans; Kidney Transplantation; Polycythemia
PubMed: 22359905
DOI: No ID Found -
Blood Reviews Dec 1991Patients with apparent polycythaemia are characterised by a raised packed cell volume (PCV; males above 0.51, females above 0.48) but normal red cell mass (RCM; less... (Review)
Review
Patients with apparent polycythaemia are characterised by a raised packed cell volume (PCV; males above 0.51, females above 0.48) but normal red cell mass (RCM; less than 25% greater than predicted). Prediction and interpretation of RCM and PV should be based on height and weight, since the use of body weight alone is misleading. Patients with PCV values up to 0.60 may have apparent polycythaemia but only 18% have a reduced PV (relative polycythaemia). Therefore, the most common cause of the raised PCV is a change in RCM and/or PV within their normal ranges. The clinical associations and possible causes for the RCM/PV changes include male sex, obesity, dehydration, diuretics, smoking, hypertension, alcohol, arterial oxygen desaturation, renal disease and increased catecholamine levels. Retrospective studies of patients with apparent polycythaemia and information from other groups of polycythaemic patients suggest an increased risk of vascular occlusion, although other factors, such as hypertension and smoking, are also involved. Proposed management includes modification of possible underlying causes and examination for risk factors for vascular occlusion. In patients with PCV levels chronically above 0.54 venesection should be used, but patients with PCV values below this level should only be venesected if they are considered to be at risk of vascular occlusion. The suggested target value for PCV for venesected patients is 0.45 or below.
Topics: Hematocrit; Humans; Polycythemia; Reference Values; Risk Factors; Thrombosis
PubMed: 1782479
DOI: 10.1016/0268-960x(91)90010-a -
Klinicheskaia Meditsina May 1968
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Internal Medicine (Tokyo, Japan) Aug 2001Polycythemia is literally translated as "many cells in the blood". Only erythrocytosis (an alternative term for these disorders) produces polycythemia since leukocytes... (Review)
Review
Polycythemia is literally translated as "many cells in the blood". Only erythrocytosis (an alternative term for these disorders) produces polycythemia since leukocytes and platelets are present in blood in far smaller proportions. Polycythemia may be due to increased proliferation or decreased apoptosis of erythroid progenitors, or to delayed erythroid differentiation with an increased number of progenitor cell divisions. Prolonged red cell survival, another theoretical cause of polycythemia, has not yet been described and with intact regulatory mechanisms is unlikely to occur. Primary polycythemias result from abnormalities expressed in hematopoietic progenitors. In contrast, circulating factors cause secondary polycythemia (1). There are acquired and congenital causes of both primary and secondary polycythemia (1).
Topics: Angiotensin II; Erythropoiesis; Humans; Insulin-Like Growth Factor I; Polycythemia; Polycythemia Vera; Receptor, Angiotensin, Type 1; Receptors, Angiotensin; Receptors, Erythropoietin
PubMed: 11518102
DOI: 10.2169/internalmedicine.40.681 -
Experimental Cell Research Nov 1999Events relayed via the single transmembrane receptor for erythropoietin (Epo) are essential for the development of committed erythroid progenitor cells beyond the... (Review)
Review
Events relayed via the single transmembrane receptor for erythropoietin (Epo) are essential for the development of committed erythroid progenitor cells beyond the colony-forming unit-erythroid stage, and this clearly involves Epo's inhibition of programmed cell death (PCD). Less well resolved, however, are issues regarding the precise nature of Epo-dependent antiapoptotic mechanisms, the extent to which Epo might also promote mitogenesis and/or terminal erythroid differentiation, and the essential vs modulatory nature of certain Epo receptor cytoplasmic subdomains, signal transducing factors, and downstream pathways. Accordingly, this review focuses on the following aspects of Epo signal transduction: (1) Epo receptor/Jak2 activation mechanisms; (2) the critical vs dispensable nature of (P)Y sites and SH2 domain-encoding effectors in survival, growth, and differentiation responses; (3) primary mechanisms by which Epo inhibits PCD; (4) the integration of signals relayed by coexpressed and possibly directly interacting cytokine receptors; and (5) predictions regarding effector function which are provided by the association of certain primary and familial polycythemias with mutated human Epo receptor forms.
Topics: Humans; Polycythemia; Receptor Cross-Talk; Receptors, Erythropoietin; Signal Transduction
PubMed: 10579919
DOI: 10.1006/excr.1999.4673 -
Bailliere's Clinical Haematology Dec 1998An erythrocytosis describes an increased peripheral blood packed cell volume (PCV) and is deemed to be absolute or apparent depending on whether or not the measured red... (Review)
Review
An erythrocytosis describes an increased peripheral blood packed cell volume (PCV) and is deemed to be absolute or apparent depending on whether or not the measured red cell mass (RCM) is above the reference range. This reference range must be related to the individual's height and weight to avoid erroneous interpretations using ml/kg total body weight expressions in obesity. Absolute erythrocytoses are divided into primary, where the erythropoietic compartment is intrinsically abnormal, secondary, where the erythropoietic compartment is normal but is responding to external pathological events leading to an increased erythropoietin drive, and idiopathic, where neither a primary nor a secondary erythrocytosis can be established. Both primary and secondary erythrocytoses have congenital and acquired forms. The only form of primary acquired erythrocytosis that has been defined is the clonal myeloproliferative disorder, polycythaemia vera (PV). Modified diagnostic markers for PV are proposed. Thrombocytoses can be classified into primary, where megakaryopoiesis is intrinsically abnormal, secondary, where megakaryopoiesis is normal but increased platelet production is a reaction to some other unrelated pathology, and finally idiopathic. This latter new group would be used for patients not satisfying the criteria for primary or secondary thrombocytoses, if these were more precise and rigidly used than currently is the case. While theoretically congenital and acquired forms of primary and secondary thrombocytoses might exist, only one cause of secondary congenital thrombocytosis has been established, and primary congenital thrombocytosis has not yet been precisely defined. Primary (essential) thrombocythaemia (PT) is one of the forms of primary acquired thrombocytoses. The diagnostic criteria of PT traditionally involve the exclusion of secondary thrombocytoses and other myeloproliferative disorders but marrow histology could hold a key positive diagnostic role if objective histological features of PT were agreed.
Topics: Anthropometry; Bone Marrow; Bone Marrow Diseases; Cells, Cultured; Diagnostic Imaging; Diagnostic Tests, Routine; Erythrocyte Volume; Erythroid Precursor Cells; Erythropoietin; Female; Hematocrit; Hemoglobinopathies; Humans; Hypoxia; Kidney Diseases; Liver Diseases; Male; Neoplasms; Polycythemia; Receptors, Erythropoietin; Thrombocytosis
PubMed: 10640213
DOI: 10.1016/s0950-3536(98)80035-8 -
Schweizerische Medizinische... Aug 1981The primary polycythemias result from malignant proliferation of myeloid stem-cell. Typically, an increase of red cell mass and a decrease of erythropoietin is found. In...
The primary polycythemias result from malignant proliferation of myeloid stem-cell. Typically, an increase of red cell mass and a decrease of erythropoietin is found. In polycythemia vera, augmentation of PCV is frequently associated with elevation of WBC and platelets, as well as splenomegaly. The treatment consists of venosection and administration of P32 or cytostatics; all of which methods exhibit a specific risk. In secondary polycythemias, augmentation of red cell mass is consecutive to increased erythropoietin production; these hypererythropoietinemias may be induced by hypoxia or, rarely, may result from an inappropriate tumoral (malignant or benign) secretion. "Spurious" polycythemias are finally defined by the more or less normal red cell mass. They are divided into three groups: micropolycythemias, relative polycythemias and "spurious" chronic polycythemias. The latter are frequent and exhibit relatively important morbidity and mortality, and therefore the recently proposed new therapeutic approaches should be considered. Tobacco addiction appears to be one of the major causes of these "spurious" polycythemias.
Topics: Diagnosis, Differential; Erythrocyte Volume; Erythropoietin; Humans; Polycythemia; Polycythemia Vera; Smoking
PubMed: 7280628
DOI: No ID Found -
Lancet (London, England) Jul 1989
Review
Topics: Blood Viscosity; Bloodletting; Evaluation Studies as Topic; Heart Failure; Hematocrit; Humans; Hypoxia; Lung Diseases, Obstructive; Polycythemia
PubMed: 2567796
DOI: 10.1016/s0140-6736(89)90259-6