Immunological thrombocytopenias, as other forms of thrombocytopenia, are associated with bleeding. Occasionally, these patients manifest thrombotic events. A total of at least 29 patients were reported to have had either arterial (20 cases) or venous (9 cases) thrombosis while platelet count was less than 50 × 10(3)/μL. The most frequent clinical manifestation was a myocardial infarction. Thrombosis occurred in the large majority of patients during prednisone therapy. Patients receiving cortisone or patients with Cushing syndrome show a hypercoagulable state characterized by elevated factor VIII levels, decreased fibrinolysis, and abnormal von Willebrand factor multimers composition. The same is probably true for prednisone-treated patients with thrombocytopenia. However, the 2 conditions are not identical since prednisone is a mainly glycoactive compound, whereas cortisol produced in excess in Cushing syndrome is mainly mineraloactive. The presence of large, young, hyperactive platelets may also play a role. Prednisone-treated patients with thrombocytopenia have to be considered as potentially thrombophilic.
The reagents most frequently used for FVII activity assay are obtained by rabbit brain or human placenta. In recent years, human recombinant thromboplastins have received great attention. FVII activity in FVII deficiency is usually low, regardless of the thromboplastin used. There are a few exceptions to this rule. These are represented by FVII Padua (Arg304Gln), FVII Nagoya (Arg304Trp), and FVII (Arg79Gln). In these three instances, clear discrepancies were noted in the FVII activity depending on the thromboplastin used. This indicates that at least two areas of FVII are involved in tissue binding, namely an epidermal growth factor domain of the light chain (Arg79Gln) and the catalytic domain (Arg304), controlled by exons 4 and 8, respectively. Since these three variants are cross reactive material positive, namely they are Type 2 defects, all other variants with normal antigen should be investigated by a panel of at least three tissue thromboplastins (rabbit brain, human tissue or human recombinant, and ox brain derived) in order to obtain a satisfactory classification.
BackgroundTo investigate the number of patients with congenital thrombophilia who presented an intracardiac thrombosis.MethodsPersonal files were reevaluated together with a time-unlimited search of the literature.ResultsTwenty-five patients with intracardiac thrombosis and congenital thrombophilia have been gathered from the literature including the two personal cases. The distribution observed in thrombophilia patients is similar for left side or right side heart (9 vs 11 cases). The left ventricle and the right ventricle were involved in six or five instances, respectively. In one case, both ventricles were involved. On the contrary, the left atrium was involved in three cases whereas the right atrium was affected in six cases. In the remaining cases, more than one heart chamber was involved.ConclusionsIn “normal” subjects, left side thromboses are predominant once catheter-associated thrombi are excluded. The reason of this discrepancy lies in the greater prothrombotic effect exercised by congenital thrombophilia on venous thrombosis compared to arterial thrombosis. The relative high prevalence of cardiac thrombosis seen in patients with antithrombin and protein C deficiencies indicated that a cardiac evaluation should be carried out in all patients with these two defects.
The relationship between thrombopoietin (TPO) and its receptor cMpl in thrombocytopenic conditions has not been entirely clarified. To elucidate this interplay may expand the spectrum of indications of TPO mimetics. In this study we have explored the relationship between TPO and cMpl in platelets and megakaryocytes of 43 patients with thrombocytopenia due to idiopathic thrombocytopenic purpura (ITP), bone marrow hypoplasia, myelodysplastic syndromes (MDS), and familial thrombocytopenia. Data were compared to cMpl and TPO in patients with a normal platelet count and in patients with thrombocytosis due to essential thrombocythemia (ET). All but familial patients showed higher TPO compared to controls. All thrombocytopenic states were invariably associated with increased expression of platelet cMPL compared to healthy controls. ET patients showed normal TPO and a trend toward a reduced cMpl expression. Immunofluorescence of bone marrow sections from patients with ITP and MDS failed to show a peculiar pattern compared to controls. Multiple mechanisms regulate TPO and cMpl in thrombocytopenic conditions.
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