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Query: UMLS:C0032463 (polycythemia vera)
 3,374 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Criteria proposed by the Polycythemia Vera Study Group (PVSG) as well as several derived algorithms are currently used for the diagnosis of polycythemia vera. Although these guidelines have significantly enhanced diagnostic accuracy, they uniformly consider erythrocytosis as the requisite premise for instigating the subsequent workup. We describe the unusual presentation of a patient with microcytic anemia in whom the diagnosis of polycythemia vera was reached using the PVSG criteria and confirmed by in vitro culture assay of erythroid progenitor cells. This case highlights the usefulness of the PVSG criteria, including the red cell mass determination, for the diagnosis of polycythemia vera even in anemic patients. The roles of spleen red cell pooling and plasma volume expansion as major determinants of this unusual presentation are discussed.
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PMID:Diagnosis of polycythemia vera in an anemic patient. 1092 62

A 58 year old male heavy smoker presented with intracranial haemorrhage and erythrocytosis. Four aetiologies of polycythaemia--polycythaemia rubra vera (PRV), renal cell carcinoma, sleep apnoea syndrome, and relative polycythaemia--were found to be associated with the underlying causes of erythrocytosis. He did not fulfill the diagnostic criteria for PRV at initial presentation, but an erythropoietin independent erythroid progenitor assay identified the masked PRV, and the low post-phlebotomy erythropoietin concentration also suggested the likelihood of PRV evolution. This case demonstrates that a search for all the possible causes of erythrocytosis is warranted in patients who already have one aetiology of polycythaemia.
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PMID:Simultaneous occurrence of multiple aetiologies of polycythaemia: renal cell carcinoma, sleep apnoea syndrome, and relative polycythaemia in a smoker with masked polycythaemia rubra vera. 1096 Nov 84

The objectives of this study were to expand on recent observations that have suggested decreased thrombopoietin receptor (c-Mpl) expression in megakaryocytes of patients with polycythemia vera (PV) and agnogenic myeloid metaplasia (AMM). We applied an immunoperoxidase method with anti-c-Mpl antibody to 55 bone marrow sections from previously untreated patients with chronic myeloproliferative disorder (CMPD) or myelodysplastic syndrome (MDS). These included 8 patients with PV, 15 with AMM, 9 with essential thrombocythemia, 5 with chronic myelocytic leukemia, 9 with the 5q-syndrome and 9 with MDS with fibrosis. The findings were compared with those in four patients with reactive erythrocytosis (RE), six with immune thrombocytopenic purpura (ITP) and five normal controls. Staining intensity (SI) was moderate to strong both in normal controls and in patients with RE or ITP. In contrast, SI was weak in variable proportions of the megakaryocytes in every one of the aforementioned clonal myeloid disorders. The staining pattern (SP) was relatively uniform in MDS and heterogeneous in CMPD. Neither SI nor SP was significantly correlated with certain clinical or laboratory parameters. We concluded that altered megakaryocyte c-Mpl expression may be a nonspecific phenomenon in various subtypes of both CMPD and MDS. However, the characteristic staining patterns may complement the morphological distinction between clonal and reactive myeloproliferation.
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PMID:Megakaryocyte c-Mpl expression in chronic myeloproliferative disorders and the myelodysplastic syndrome: immunoperoxidase staining patterns and clinical correlates. 1100 52

The pathogenesis of polycythemia vera (PV), a disease involving a multipotent hematopoietic progenitor cell, is unknown. Thrombopoietin (TPO) is a newly characterized hematopoietic growth factor which regulates the production of multipotent hematopoietic progenitor cells as well as platelets. To evaluate the possibility that an abnormality in TPO-mediated signal transduction might be involved in the pathogenesis of PV, we examined TPO-induced protein tyrosine phosphorylation using platelets as a surrogate model system. Platelets were isolated from the blood of patients with PV as well as from patients with other chronic myeloproliferative disorders and control subjects. Impaired TPO-mediated platelet protein tyrosine phosphorylation was a consistent observation in patients with PV as well as those with idiopathic myelofibrosis (IMF), in contrast to patients with essential thrombocytosis, chronic myelogenous leukemia, secondary erythrocytosis, iron deficiency anemia, hemochromatosis, or normal volunteers. Thrombin-mediated platelet protein tyrosine phosphorylation was intact in PV platelets as was expression of the appropriate tyrosine kinases and their cognate substrates. However, expression of the platelet TPO receptor, Mpl, as determined by immunoblotting, chemical crosslinking or flow cytometry was markedly reduced or absent in 34 of 34 PV patients and also in 13 of 14 IMF patients. Impaired TPO-induced protein tyrosine phosphorylation in PV and IMF platelets was uniformly associated with markedly reduced or absent expression of Mpl. We conclude that reduced expression of Mpl is a phenotypic characteristic of platelets from patients with PV and IMF. The abnormality appears to distinguish PV from other forms of erythrocytosis and may be involved in the platelet function defect associated with PV.
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PMID:A novel thrombopoietin signaling defect in polycythemia vera platelets. 1101 90

There is no single diagnostic marker for the only known type of primary acquired erythrocytosis, polycythemia vera (PV). The Polycythemia Vera Study Group (PVSG) used a combination of major and minor diagnostic criteria. However, these guidelines have some limitations and in the presence of newer diagnostic tools, have been re-evaluated. The recommendations of the Radionuclide Panel of the International Council for Standardization Hematology based on surface area are recommended over red blood cell mass (RCM) mL/kg expressions. Absolute erythrocytosis can be assumed in males and females with packed cell volume (PCV) values greater than 0.60 and greater than 0.56, respectively. A satisfactory strategy of investigation for a secondary erythrocytosis must be used. Hypoxemia, as well as renal and hepatic pathology, must be excluded. In unexplained absolute erythrocytoses, pO(2)(50) values and serum erythropoietin (EPO) levels should be examined. The latter can be disappointing in the confirmation of a secondary erythrocytosis, but elevated values contraindicate a diagnosis of a primary erythrocytosis. Establishment of a clonal marrow population supports a diagnosis of PV. Thus an acquired karyotypic abnormality is a major criterion. Palpable splenomegaly remains an important diagnostic marker. Scanning techniques to demonstrate splenic enlargement should be used with caution. Allowance must be made for interobserver and intraobserver differences and variation in normal spleen size with age and size of the subject. Splenomegaly demonstrated in this way should be taken as a minor criterion. An increased neutrophil count (>10 x 10(9)/L and >12.5 x 10(9)/L in smokers) is readily measurable and should replace total white blood cell count. The error in measurement of neutrophil alkaline phosphatase (NAP) score is large, making it an unsuitable diagnostic criterion. Neutrophil and platelet counts (>400 x 10(9)/L) should be taken as separate minor criteria. Endogenous erythroid colonies (EEC) grown from the peripheral blood have been used as a marker of PV, but it is an expensive technique that is not standardized and not totally specific for PV. Low serum EPO values found in the majority of patients with PV should hold a linked minor criterion position with EEC. Expert opinions should be obtained if bone marrow histology is to be used in the diagnosis of PV, but histology holds an important role in confirming the diagnosis. Semin Hematol 38(suppl 2):21-24.
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PMID:Evaluation of diagnostic criteria in polycythemia vera. 1124 98

n vitro, rheological studies establish that whole blood viscosity and yield stress are high in patients with an erythrocytosis. However, a number of factors ensure that these patients, under physiological conditions, do not show the clinical features observed in other hyperviscosity states. These include red cell axial migration in flowing blood and "plug flow" in the largest vessels. In addition, a small increase in vessel diameter leads to large increases in blood flow, and generally high blood flows produce the lowest blood viscosity values. The increased hemoglobin levels and the increase in oxygen-carrying capacity at high hematocrit values compensate for the tissue hypoxia. In the "non-hypoxemic" erythrocytoses (polycythemia vera, idiopathic and apparent erythrocytosis), there is an increased incidence of vascular occlusion in untreated patients. The reasons for this include reduced peripheral blood flow, increased platelet-vessel wall interactions, and the demonstrated in vitro hyperviscosity which comes into play with abnormally low flow, seen in vivo under pathological conditions. In the erythrocytosis of hypoxemic lung disease and its associated hypoxemia, pulmonary vasoconstriction enhances susceptibility to hyperviscosity effects in particular. Moreover, the vasoconstriction caused by the hypoxemia prevents the normal adaptive changes of increased vessel diameter. Microcytic hypochromic red cell changes of iron deficiency do not cause a higher viscosity value at any given hematocrit value compared with normal red cells. However, in hypoxemic states oxygen-carrying capacity should be maximized, since the hemoglobin value is disproportionately lower at any given hematocrit in the presence of microcytic hypochromic cells compared with normal red cells.
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PMID:Hemorheology in the erythrocytoses. 1137 90

This review focuses on polycythemia vera (PV)-its diagnosis, cellular and genetic pathology, and management. In Section I, Dr. Pearson, with Drs. Messinezy and Westwood, reviews the diagnostic challenge of the investigation of patients with a raised hematocrit. The suggested approach divides patients on their red cell mass (RCM) results into those with absolute (raised RCM) and apparent (normal RCM) erythrocytosis. A standardized series of investigations is proposed for those with an absolute erythrocytosis to confirm the presence of a primary (PV) or secondary erythrocytosis, with abnormal and normal erythropoietic compartments respectively, leaving a heterogenous group, idiopathic erythrocytosis, where the cause cannot be established. Since there is no single diagnostic test for PV, its presence is confirmed following the use of updated diagnostic criteria and confirmatory marrow histology. In Section II, Dr. Green with Drs. Bench, Huntly, and Nacheva reviews the evidence from studies of X chromosome inactivation patterns that support the concept that PV results from clonal expansion of a transformed hemopoietic stem cell. Analyses of the pattern of erythroid and myeloid colony growth have demonstrated abnormal responses to several cytokines, raising the possibility of a defect in a signal transduction pathway shared by several growth factors. A number of cytogenetic and molecular approaches are now focused on defining the molecular lesion(s). In the last section, Dr. Barbui with Dr. Finazzi addresses the complications of PV, notably thrombosis, myelofibrosis and acute leukemia. Following an evaluation of published data, a management approach is proposed. All patients should undergo phlebotomy to keep the hematocrit (Hct) below 0.45, which may be all that is required in those at low thrombotic risk and with stable disease. In those at high thrombotic risk or with progressive thrombocytosis or splenomegaly, a myelosuppressive agent should be used. Hydroxyurea has a role at all ages, but (32)P or busulfan may be used in the elderly. In younger patients, interferon-alpha or anagrelide should be considered. Low-dose aspirin should be used in those with thrombotic or ischemic complications.
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PMID:A Polycythemia Vera Updated: Diagnosis, Pathobiology, and Treatment. 1170 35

Polycythaemia vera was diagnosed in a three-year-old domestic shorthaired cat referred because of seizures and a high packed cell volume (PCV). Laboratory examination revealed severe erythrocytosis (PCV 79 per cent). Diagnosis was reached by excluding causes for relative and secondary absolute polycythaemia. As phlebotomy proved impossible for initial treatment due to hyperviscosity, four leeches were used to suck blood and the PCV was consequently reduced to 64 per cent. A further 24 hours later, when bleeding at the sites of sucking had stopped, the PCV was 56 per cent. Long-term management of the condition was achieved with hydroxyurea (100 mg/cat once daily) and intermittent phlebotomy. Initial treatment using leeches in cases of polycythaemia vera is a simple, non-invasive, well tolerated and effective method where phlebotomy is not possible.
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PMID:Leeching as initial treatment in a cat with polycythaemia vera. 1172 85

The Polycythemia Vera Study Group (PVSG) was organized in 1967 to identify the optimal approach to the diagnosis and treatment of polycythemia vera (PV). Nevertheless, a systematic assessment of US physicians' approach to PV has not been performed. To determine practice patterns in the management of PV, a random sample of the US American Society of Hematology (ASH) membership was surveyed. Thirty-three percent of 3000 surveys were returned. Significant variations in diagnostic and therapeutic approach were evident by region, practice type, specialty, and clinical experience. Red cell volume determinations (78% of respondents), serum erythropoietin levels (76%), and arterial blood gases (75%) were the most frequent tests used in the diagnosis of PV. Sixty-nine percent of physicians use phlebotomy as their first choice for erythrocytosis. Phlebotomy plus hydroxyurea (27.8%) and hydroxyurea alone (10%) were used less often. Despite PVSG recommendations, almost 16% of physicians used a target hematocrit of 0.55 (50%) or 0.55 (55%) for phlebotomy therapy. Eighty-two percent of physicians treated thrombocytosis only when platelet counts exceeded 1000 x 10(9)/L (1 000 000/microL) or in the event of symptoms. Hydroxyurea (62.8%) and anagrelide (35.4%) were the primary agents used to treat thrombocytosis. Thus, this national survey of US hematologists and oncologists has identified substantial variation in the approach to the diagnosis and treatment of PV. A significant minority of physicians undertreat erythrocytosis, and little consensus exists regarding the treatment of thrombocytosis.
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PMID:The diagnosis and management of polycythemia vera in the era since the Polycythemia Vera Study Group: a survey of American Society of Hematology members' practice patterns. 1183 Apr 59

The association of hepatocellular carcinoma (HCC) and polycythemia vera in a middle-aged caucasian man is described for the first time in this case report. The report underlines the necessity and the importance of a full, evidence-based investigation of the nature of polyglobuly in the course of HCC, a condition known to be associated to erythrocytosis, so far usually considered secondary to HCC, and not primary.
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PMID:[Association between hepatocellular carcinoma and polycythemia vera]. 1185 Sep 96


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