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PubMed1991

Generation of arachidonic acid metabolites from stimulated whole blood in patients with chronic myeloproliferative disorders.

We have evaluated the arachidonic acid (AA) metabolism in patients with myeloproliferative disorders (MPD). In essential thrombocythemia (ET), the generation of thromboxane B2 was found significantly reduced and inversely correlated with platelet count. Polycythemia vera (PV) patients showed an increased formation of this metabolite of AA. Prostaglandin E2 and 6-keto-PGF1 alpha generation were markedly reduced in patients with chronic myelogenous leukemia. Our study confirms that the arachidonate metabolism is frequently deranged in patients with MPD. The opposite changes in thromboxane formation in ET and PV could be one of the factors responsible for the different incidences of thrombotic and hemorrhagic complications in these diseases.

6-Ketoprostaglandin F1 alpha↗
PubMed2001

A long-term retrospective study of young women with essential thrombocythemia.

OBJECTIVE: To describe presenting clinical manifestations, long-term disease complications, prognostic indicators, and outcome of pregnancy for women younger than 50 years with essential thrombocythemia. PATIENTS AND METHODS: We retrospectively reviewed the records of all patients with essential thrombocythemia evaluated at Mayo Clinic, Rochester, Minn, between 1969 and 1991 and identified 74 young women (median age, 35 years; range, 18-48 years) with essential thrombocythemia. The diagnosis was based on previously established criteria. Median follow-up was 9.2 years (range, 0.2-26.2 years). RESULTS: Overall survival was similar to that of an age- and sex-matched control population. Thrombotic events (except superficial thrombophlebitis) occurred at and after diagnosis in 11 patients (15%) and 13 patients (18%), respectively. A history of thrombosis at diagnosis was significantly associated with recurrent thrombosis (P = .03). A platelet count higher than 1500 x 10(9)/L at diagnosis was significantly associated with gastrointestinal tract bleeding and subsequent development of venous (but not arterial) thrombosis (P = .04). Major hemorrhagic events occurred in only 3 patients (4%) after diagnosis. Only 1 patient developed acute leukemia. Thirty-four pregnancies occurred in 18 patients. Of these, 17 (50%) resulted in live births. Of the 17 patients with unsuccessful pregnancies, 14 had spontaneous abortions, 1 had an ectopic pregnancy, and 2 had elective abortions. Preconception platelet count, thrombotic history, or specific therapy was not useful in predicting pregnancy outcome. CONCLUSION: Young women with essential thrombocythemia can expect long survival with a low incidence of life-threatening thrombohemorrhagic complications or acute leukemia. There is an increased incidence of first-trimester miscarriages that may not be influenced by specific therapy.

Adolescent↗
PubMed1989

Recombinant interferon-alpha therapy of Philadelphia chromosome-negative myeloproliferative disorders with thrombocytosis.

PURPOSE: The clinical course of patients with myeloproliferative disorders and excessive thrombocytosis may be complicated by serious hemorrhagic or thrombotic events. We have previously reported that interferon-alpha can control severe refractory thrombocytosis in patients with advanced chronic myelogenous leukemia. Therefore, we treated a group of thrombocythemic patients with Ph-negative myeloproliferative disorders, including polycythemia vera and essential thrombocythemia, with recombinant interferon-alpha (rIFN-alpha 2a). PATIENTS AND METHODS: Eight patients with profound elevations in platelet counts received a median induction dose of 5.4 X 10(6) U/day (range, 5.0 to 10.0 X 10(6) U/day) of rIFN-alpha 2a administered intramuscularly or subcutaneously. RESULTS: We observed a significant decline in platelet counts from a median baseline value of 1,929 X 10(9)/L (range, 960 to 2,960 X 10(9)/L) to a median posttreatment value of 431 X 10(9)/L (range, 71 to 1,150 X 10(9)/L) (p less than 0.01). Concomitantly, white blood cell counts declined from a median baseline value of 20.8 X 10(9)/L (range, 10.5 to 40.8 X 10(9)/L) to a median posttreatment value of 6.1 X 10(9)/L (range, 2.9 to 29.0 X 10(9)/L) (p less than 0.02). Correction of thrombocytosis was rapid, with a median of only eight days from the start of therapy to the achievement of a platelet count less than 1,000 X 10(9)/L. Six of eight patients have shown an ongoing response with a median follow-up period of 11 months (range, one to 30 months). There have been no bleeding or thrombotic events during the study. Side effects of rIFN-alpha 2a therapy consisted of fever and flu-like symptoms, with tachyphylaxis developing after one to two weeks of therapy. CONCLUSION: Our observations suggest that alpha interferon may be a promising therapeutic agent for myeloproliferative disorders characterized by thrombocytosis.

Adult↗
PubMed2001

Management of patients with essential thrombocythemia: current concepts and perspectives.

Essential thrombocythemia must now be regarded as a heterogeneous disease. Recent availability of clonality studies have repeatedly shown that a significant number of female patients diagnosed as E.T. according the most stringent criteria had a definitely polyclonal myelopoiesis. Although the incidence of patients newly diagnosed every year is low, there is in fact a conspicuous population of E.T., followed as outpatients in every department of hematology or internal medicine, including a large number of young females. These eventualities should be integrated in further discussions of the benefit/risk ratio of cytoreduction with the presently available drugs. The combination of several evidence-based data is the basis of a widely accepted stratification of high-risk patients defined by any of the following features. Age > 60 to 65. History of thrombosis or embolic or major ischemic events. Platelet counts in excess of 1000 or 1500 x 10(9)/L. In the question of chemotherapy in E.T., growing concern comes from the potential leukemogenic risk associated with the presently available drugs and extends beyond Melphalan, Busulfan and other alkylating agents and includes non-alkylating agents like Hydroxyurea. At the same time, much attention has been paid to the introduction of very precise initial diagnostic criteria directed to elimination of other myeloproliferative or myelodysplastic disorders with an increased risk of transformation. Present treatment of E.T. is a compromise between prevention of E.T. related thrombotic and bleeding complications on one hand and long term side effects and toxicity of the presently available drugs on the other hand. The recent availability of non mutagenic drugs like Interferon and most of all Anagrelide; the recognition of the role of antiaggregating agents in the treatment of platelet related microvascular ischemic events gives the opportunity for further comparative prospective trials. The use of aspirin in the management of pregnant E.T. patients is now widely accepted but there is still controversies concerning the use of Interferon in this situation.

Adult↗
PubMed2002

Markers of platelet activation and platelet-leukocyte interaction in patients with myeloproliferative syndromes.

INTRODUCTION: Changes in platelet count and function contribute to thrombo-hemorrhagic episodes in chronic myeloproliferative syndromes (MPS). We used flow cytometry to study platelet-leukocyte conjugates and markers of platelet activation in patients with MPS. METHODS: Whole blood from patients with chronic myelogenous leukemia (CML), polycythemia vera (PV), chronic myelofibrosis (MF), and essential thrombocythemia (ET) and from healthy volunteers was prepared for flow cytometry. Platelet microparticles and platelet microaggregates were identified with anti-CD42b and forward scatter, activated platelets with anti-CD62p. Anti-CD42b, anti-CD14, and anti-CD45 were used to study platelet-leukocyte conjugates. RESULTS: The percentage of CD62p-positive platelets was elevated in all myeloproliferate syndrome subtypes. The median percentage of platelet microparticles was 5.2% in controls and significantly higher in PV (12.0%), MF (11.0%), and ET (11.0%, all p<0.05). There was an increased percentage of platelet-neutrophil conjugates in patients with PV (8.3%) and ET (10.4%) compared to normal controls (6.8%, all p<0.05). Platelet-monocyte conjugates were 8.0% in controls and elevated in PV (15.4%) and ET (15.0%, all p<0.05). Patients with a history of venous or arterial thrombotic events had slightly less platelet-leukocyte conjugates and slightly more microparticles than patients without thrombosis; however, this difference was not statistically significant. CONCLUSIONS: These findings suggest that platelet-leukocyte conjugate formation occurs in myeloproliferative syndromes and indicates platelet activation. Also, platelet microparticles are elevated and might provide a catalytic surface for thrombin generation. This could explain the clinical observation that patients with myeloproliferative syndromes have an increased risk to experience arterial or venous thrombotic events.

Adult↗
PubMed2002

[Therapeutic effectiveness of ranimustine chemotherapy for essential thrombocythemia in the elderly].

We studied the therapeutic effectiveness of chemotherapy by ranimustine (MCNU) for essential thrombocythemia (ET) in 14 ET patients over 60 years of age. The median age was 73 years (range: 61-88 years), and the male/female ratio was 6:8. The mean platelet counts before chemotherapy was 1,157 +/- 28.4 x 10(3)/microliter. Five of them had been referred because of thrombotic episodes before admission to our hospital, while one was referred because of nasal bleeding. The platelet counts were maintained at a level below 500 x 10(3)/microliter by intravenous administration of MCNU in 12 patients and below 700 x 10(3)/microliter in two patients. One of the patients suffered cerebral infarction during MCNU therapy. No other patient suffered thrombotic episodes during MCNU therapy. The patient who was referred because of nasal bleeding had no hemorrhagic episode during control of platelet counts by chemotherapy. MCNU chemotherapy appears effective for the prevention of thrombosis and bleeding in ET.

Aged↗
PubMed1996

Treatment strategies in essential thrombocythemia. A critical appraisal of various experiences in different centers.

The therapeutic strategy in patients with Essential Thrombocythemia (ET) is a difficult balance between the prevention of bleeding and thrombotic complications and the risks of drug side effects and toxicity. Major bleeding is rare and seem to be related to higher platelet counts: therefore, a platelet count over 1500 x 10(9)/L is generally regarded as an indication for cytoreduction. Thrombotic complications include microvascular occlusive symptoms, which are reversible with low-dose aspirin, and large vessels thrombosis. The risk of major thrombosis is higher in ET patients aged more than 60 ys. and with previous occlusive event. In this high-risk group, the non-alkylating agent hydroxyurea (HU) significantly reduces the rate of vascular complications and has emerged as the treatment of choice. However, the long-term risk/benefit of HU remains disputed because its leukemogenic potential has not been ruled out. This holds also for other myelosuppressive agents, such as busulphan and pipobroman. Other drugs of particular interest for young patients include recombinant alpha-interferon (IFN) and Anagrelide. Both of them are effective in lowering platelet count, but their efficacy in reducing clinical complications remains to be demonstrated. However, both IFN and Anagrelide have shown to have frequent and clinically important side effects. Thus, further clinical studies are required to establish their role in the strategy of ET patient treatment.

Adult↗
PubMed1996

Essential thrombocythemia in an infant.

PURPOSE: To report the unusual occurrence of essential thrombocythemia (ET) in a 5-month-old infant. PATIENTS AND METHODS: The child was referred by her pediatrician for a high platelet count detected on routine blood testing. The child was asymptomatic except for failure to thrive. Diagnostic tests to rule out secondary causes of thrombocytosis as well as myeloproliferative syndrome were done. RESULTS: The platelet count persisted at > 1,000,000/microliters, and no secondary cause could be established. The bone marrow aspirate and biopsy showed normal cellularity, no fibrosis, orderly maturation, and normal morphology of all three cell lines, with only an increase in the number of megakaryocytes. A diagnosis of ET was established as per the Polycythemia Vera Study Group criteria. In view of the young age of the patient and asymptomatic course of the disease, we decided to observe the child only, reserving antiplatelet agents for use in the event of a thromboembolic or hemorrhagic episode. CONCLUSIONS: This is the youngest known child with ET. We believe that conservative observation is warranted in an asymptomatic child. The child is currently doing well and is asymptomatic 4.5 years after diagnosis.

Female↗
PubMed2003

Platelet-mediated microvascular inflammation and thrombosis in thrombocythemia vera: a distinct aspirin-responsive arterial thrombophilia, which transforms into a bleeding diathesis at increasing platelet counts.

Erythromelalgia is the main, pathognomonic and presenting symptom in patients with essential thrombocythemia and thrombocythemia associated with polycythemia vera. Complete relief from erythromelalgic and acrocyanotic pain is obtained with the cyclooxygenase inhibitors aspirin and indomethacin, but not with sodiumsalicylate, dipyridamol, sulfinpyrozone and ticlopedine. Thus, cyclooxygenase metabolites are necessary for erythromelalgia to develop. Local platelet consumption in erythromelalgic areas became evident by the demonstration of arteriolar fibromuscular intimal proliferation and occlusions by platelet-rich thrombi in skin biopsies, by the findings of shortened platelet survival times, significant higher levels of platelet activation markers beta-thromboglobulin, thrombomoduline and increased urinary thromboxane B2 excretion in thrombocythemia patients suffering from erythromelalgia. Aspirin treatment of erythromelalgia in thrombocythemia patients resulted in the disappearance of the erythromelalgic, thrombotic signs and symptoms, correction of the shortened platelet survival times, and a significant reduction of the increased levels of beta-TG, PF4, TM and urinary TxB2 excretion to normal. Erythromelalgia is frequently preceded or followed by atypical transient neurologic, ocular or coronary ischemic symptoms, which specifically respond to low-dose aspirin or reduction of platelet counts to normal. The broad spectrum of acropareshesias, erythromelalgia and acrocyanotic ischemia together with the episodic and transient atypical TIAs and ocular or coronary ischemic symptoms are caused by spontaneous activation and aggregation of hypersensitive platelets in the end-arterial microvasculature involving the peripheral, cerebral and coronary circulation of thrombocythemia patients. These microvascular circulation ischemic disturbances in thrombocythemia vera already occur at platelet counts in excess of 400 x 10(9) l(-1). Low-dose aspirin is highly effective and safe in the cure and prevention of thrombotic and ischemic events and does not elicit bleedings at platelet counts below 1000 x 10(9) l(-1). Spontaneous hemorrhages usually occur at very high platelet counts far in excess of 1000 x 10(9) l(-1) (HT) due to an acquired von Willebrand factor deficiency at increasing platelet counts. At platelet counts between 1000 and 2000 x 10(9) l(-1), thrombosis and bleeding (ETT and HT) frequently occur in sequence or paradoxically and low-dose aspirin does prevent thrombotic complications but aggravates or may elicit bleeding symptoms. Reduction of the platelet count to below 1000 x 10(9) l(-1) by platelet lowering agents usually results in the disappearance of the bleeding tendency and improvement of the von Willebrand syndrome, but the thrombotic tendency persists as long as platelet counts are above the upper limit of normal.

Aspirin↗
PubMedDate not supplied

Treatment of children with anagrelide for thrombocythemia.

PURPOSE: Essential thrombocythemia (ET) is a rare myeloproliferative disease characterized by hyperproliferation of megakaryocytes and persistent elevation of platelets. Major complications are thrombosis, bleeding, and microvascular occlusive symptoms, sometimes resulting in serious morbidity. In patients with platelet counts > 1000 x 10(9)/l, cytoreduction is important to reduce the risk for thrombotic or hemorrhagic events. However, the frequent side effects and the carcinogenic potential of many cytoreductive agents limit their use, especially in younger patients. Anagrelide, a noncarcinogenic agent with moderate toxicity, has been successfully used in adult patients with ET, but experience with anagrelide in pediatric patients with ET is limited. PATIENTS AND METHODS: Three children who received anagrelide (Induction dose 1 mg/day, maintenance dose 1 to 2.5 mg/day) as therapy for ET are described. RESULTS: All children had a rapid and marked decline of their platelet counts, and only one child developed mild and transient abdominal side effects. CONCLUSIONS: Treatment with anagrelide seems to be a promising approach for children with ET. It should be considered as first-line therapy because of its selective activity against platelet production, tolerable toxicity, suspected negligible cancerigenic effect, and the possibility of oral administration.

Adolescent↗
PubMedDate not supplied

[Essential thrombocythemia: a 35-year experience and review of the literature].

Essential thrombocythemia (ET) is a clonal myeloproliferative disorder characterized by an uncontrolled rise in peripheral blood platelet count. The aim of this report was to determine the clinical and laboratory data of this disease in a 35 years revision. Of the patients with the diagnosis of ET, we selected those who fulfilled five of the six diagnostic criteria proposed by the Poli Vera Study Group. We found 14 cases (10 female and 4 male) with a median age of 54.5 years (range 29-74). The most frequent initial clinical finding was hemorrhage and in four cases the diagnosis was preoperative. Median platelet count was 1,355 x 10(9)/L (range 600 to 3,750). One case had iron deficiency which was corrected before ET was diagnosed. None has evolved to acute leukemia. Initially, most of the cases were treated with busulphan and two received alpha-interferon which was promptly changed to busulphan because of secondary effects. Three patients have died due to hemorrhagic complications and one due to thrombosis. ET has a low frequency in our country and must be considered an exclusion diagnosis. Iron deficiency may mask the diagnosis specially in the cases with a platelet count not very high. Treatment can provide in general a long survival of good quality of life.

Adult↗
PubMed1988

[Clinical characterization of essential thrombocythemia in comparison with other myeloproliferative diseases and reactive thrombocytoses].

60 patients with essential thrombocythemia (ET) have been retrospectively and prospectively followed from 1974 through 1987. The presenting signs and symptoms and the course of the disease were analyzed and compared to 10 patients with persisting reactive thrombocytosis selected from 6,000 patients with reactive thrombocytosis and to 50 patients with other myeloproliferative diseases. 54 ET-patients presented with complications, 46 with thrombembolic, 3 with hemorrhagic problems and 5 with thrombembolic and hemorrhagic problems. In 6 patients ET was detected accidentally. Disturbances of the microcirculation, mainly of the fingers and the toes, were the most frequent symptom. The average maximal platelet count was 1,207,000/microliter. The average platelet count at diagnosis was 880,000/microliter. 16 patients had an elevation of the serum creatinine at diagnosis, which deteriorated during the course of the disease. Bone marrow examinations were performed in 56 patients, histology in 48 patients, cytology in 29 patients. In contrast to the clinical diagnosis the histological diagnosis was in 4 cases each polycythemia vera and myeloproliferative syndrome without further specification. 12 patients died thus far. The causes of death were thrombembolic complications in 9, acute leukemia in 2 patients, in 1 patient the cause of death is not known. 10 years after diagnosis 61% of the patients are still alive. It appears that ET is a more important risk factor for the disturbances of the micro- and macrocirculation than has been recognized until now. ET is, if thrombembolic complications are avoided, a disease with a relatively benign course.

Aged↗
PubMed1998

Treatment of polycythaemia vera and essential thrombocythaemia.

The clinical course in both polycythaemia vera (PV) and essential thrombocythaemia (ET) is characterized by significant thrombohaemorrhagic complications and variable risk of disease transformation into myeloid metaplasia with myelofibrosis or acute myeloid leukaemia. Randomized studies have shown that the risk of thrombosis was significantly reduced in ET with the use of hydroxyurea (HU) and in PV with the use of chlorambucil or 32P. However, the use of chlorambucil or 32P has been associated with an increased risk of leukaemic transformation. Subsequently, other studies have suggested that both HU and pipobroman may be less leukaemogenic and as effective as chlorambucil and 32P for preventing thrombosis in PV. However, the results from these prospective studies have raised concern that even HU and pipobroman may be associated with excess leukaemic events in both ET and PV. The recent introduction of anagrelide as a specific platelet-lowering agent, the demonstration of treatment efficacy with interferon-alpha, and the revived interest in using low-dose acetylsalicylic acid provide the opportunity to initiate prospective randomized studies incorporating these treatments.

Adult↗
PubMed2003

Acquired thrombophilia in pregnancy: essential thrombocythemia.

The management of pregnant patients with essential thrombocythemia (ET) is a difficult problem. The clinical course of ET is mainly determined by thromboembolic complications. Pregnancy itself is a physiological hypercoagulable state. When ET affects women during pregnancy, an adverse outcome caused by thrombotic complications is a matter of concern. We reviewed 155 pregnancies in 86 women with ET. The success rate (baby alive) was 59%. First-trimester abortion was the most frequent complication and occurred in 31% of pregnancies. Placental infarction caused by thrombosis seemed to be the most consistent pathologic event. Maternal thrombotic or hemorrhagic complications were rare but were more common than those seen in normal pregnancy. Pregnancy itself does not appear to affect adversely the natural course and prognosis of ET. A meta-analysis revealed a significant benefit for aspirin in comparison to no treatment. If cytoreductive therapy becomes necessary, interferon alpha appears to be the drug of choice. The value of heparin prophylaxis has not been established but may have a role in selected cases.

Anticoagulants↗
PubMed1996

Bleeding time and platelet function in essential thrombocythemia and other myeloproliferative syndromes.

Bleeding time (BT) and platelet function tests have been widely used in patients with essential thrombocythemia (ET), with the aim to support diagnosis and to identify laboratory predictors of haemorrhagic and thrombotic complications. BT is significantly prolonged in 7-19% of ET patients and several functional abnormalities have been observed in platelet structure, biochemistry and survival. However, the attempt to relate these in vivo and in vitro platelet dysfunctions with diagnosis or clinical sequelae has been generally disappointing. Therefore, BT and platelet function tests are currently not recommended in the initial evaluation or during the follow-up of patients with ET, unless in the setting of a clinical or biological study. A noteworthy exception is represented by a subset of patients characterized by very high platelet count (> 1500 x 10(9)/L) and bleeding symptoms, who can have an acquired von Willebrand disease. In these cases, prolonged BT and abnormal multimeric pattern of von Willebrand factor are useful for diagnosing and monitoring this acquired hemorrhagic disease. BT and platelet function tests should be included in the baseline evaluation of ET patients enrolled in prospective clinical trials aiming assess their predictive role on clinical end-points.

Arachidonic Acid↗
PubMed1990

[Clinical study on heterogeneity of chronic myelomonocytic leukemia].

We examined fourteen patients with chronic myelomonocytic leukemia (CMMoL) according to the following staging criteria at diagnosis; Group A: bone marrow (BM) blast less than 5% (eight cases), Group B; BM blast more than 5% and less than 30% (five cases), Group C; BM blast more than 30% (one case). Compared with Group A, Group B patients have much more peripheral blood leukocyte, granulocyte and monocyte counts, LDH level, and serum and urine lysozyme levels. Two of the five Group B cases transformed to acute leukemia (BC) within one and a half year, and other three patients died of infection and hemorrhage within a year. On the contrary, three of the eight Group A patients survived four years, and transformation to acute leukemia occurred in only one case after four years. Autopsy revealed multiple organ infiltration of monocytoid granulocytes on the patients with advanced stage and more bone marrow blasts. Two cases have coexistence of myeloproliferative disorders, one with essential thrombocythemia, and another with myelofibrosis, which, later, transformed to acute leukemia. And a Group C patient transformed to chronic phase with chemotherapy, and maintained the state for six years, but at the end stage, mature monocytes increased and pancytopenia developed. These findings indicate the heterogeneity of CMMoL in respect of the disease stage and the coexistence of other myeloproliferative disorders.

Aged↗