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Results for “Factor XI Deficiency”
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Diagnosis and treatment of inherited bleeding disorders.
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Practical guidelines for the clinical use of plasma.
Despite differences in the composition of fresh frozen plasma (FFP) and solvent/detergent-treated plasma, prospective controlled clinical trials have not revealed any significant difference in clinical efficacy and tolerance between the two types of plasma. Evidence of the clinical efficacy of plasma is mainly based on expert opinion, case reports, and on controlled and uncontrolled observational studies. The application of plasma without laboratory analysis to verify the coagulopathy is normally not justified. With the exception of emergency situations when timely clotting assay results are not available, the administration of plasma in coagulopathy must be verified both clinically and by laboratory analysis before plasma is administered. The rapid infusion of at least 10 ml plasma/kg of body weight is required to increase the respective plasma protein levels significantly. Based on the present state of knowledge, plasma is indicated for complex coagulopathy associated with manifest or imminent bleeding in massive transfusion, disseminated intravascular coagulation, and liver disease. Therapeutic plasma exchange with 40 ml plasma/kg of body weight is the treatment of first choice in acute thrombotic-thrombocytopenic purpura-adult hemolytic uremic syndrome (TTP-HUS). A rare indication is the treatment or prevention of bleeding in congenital factor V or factor XI deficiency, plasma exchange in neonates with severe hemolysis or hyperbilirubinemia, and filling of the oxygenator in extracorporeal membrane oxygenation (ECMO) in neonates. Prothrombin complex concentrates should be preferred to plasma for the reversal of oral anticoagulation in emergency situations, since controlled studies have shown a minor efficacy of plasma. Side effects resulting from the administration of plasma are rare but have to be considered.
The contact activation system: biochemistry and interactions of these surface-mediated defense reactions.
This review is intended to be a critical state-of-the-art overview of the activation and inhibition of the proteins (factor XII, prekallikrein, high molecular weight kininogen, and factor XI) of the contact phase of coagulation. Specifically, this review will reconsider the concept of the reciprocal activation of the proteases of the contact phase of coagulation, factor XII, and prekallikrein, in light of much recent evidence indicating that factor XII, itself, autoactivates when associated with negatively charged surfaces. In addition, the mechanisms for amplification of activation of the proteins of the contact phase of coagulation will be discussed from the pivotal role of high molecular weight kininogen, or one of its altered forms, serving as a cofactor to order the activation of the zymogens it is associated with. The role and relative importance of each of the naturally occurring plasma protease inhibitors (C1-inhibitor, alpha-2-macroglobulin, alpha-1-antitrypsin, antithrombin III, and alpha-1-antiplasmin) will be assessed as they relate to the dampening of contact phase activation. Finally, the contact phase of coagulation activation will be discussed not only as a plasma proteolytic mechanism, but also as it interacts with platelets.
Menorrhagia from a haematologist's point of view. Part II: management.
The management of menorrhagia has until recently been the domain of the gynaecologist. As haematologists, we are now addressing the issue of optimal management of menorrhagia in our patients with bleeding disorders. Addressing three life periods, the menarche, reproductive years, and postchildbearing years, this review will discuss the use of oral contraceptive agents, antifibrinolytics, non-steroidal anti-inflammatory drugs, intranasal DDAVP and the new levonorgestrel-impregnated IUD. Management of specific bleeding disorders will also be reviewed for von Willebrand disease, haemophilia A and B carriers, women with factor XI deficiency and PAI-1 deficiency.
Contact factors in health and disease.
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Unexpected bleeding after elective nasal surgery.
In 780 patients undergoing elective nasal surgery, the incidence of excessive bleeding was 3.6% (28 patients); of severe bleeding, 0.9% (7 patients). In most patients, effective treatment was to repack the nose and cauterize a bleeding site, or to suture an open area either in the incision or at the columella-septum junction. Contributing to the hemorrhage in 1 patient was aspirin ingestion, and in another, an unrecognized Factor XI deficiency. Although the excessive bleeding in these patients could probably have been prevented by obtaining a better history, in others it could not have been. Because of its unpredictability, bleeding as a complication must be discussed frankly with the patient.
Surgery in patients with congenital disorders of blood coagulation.
Surgical procedures on patients with congenital disorders of blood coagulation can be performed with a high degree of confidence and an acceptable incidence of complications. During the period 1960-1975, 42 patients with congenital disorders of blood coagulation underwent 94 operative procedures at the New York Hopital-Cornell Medical Center. The coagulation defect was diagnosed preoperatively, in nearly all patients. Careful hematologic management, including specific factor replacement, is essential. The importance of meticulous hemostasis at surgery and careful monitoring of blood coagulation in the postoperative period is strongly emphasized.
Platelets and initiation of intrinsic clotting.
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The use of levonorgestrel-releasing intrauterine system for treatment of menorrhagia in women with inherited bleeding disorders.
BACKGROUND: The levonorgestrel-releasing intrauterine system (LNG-IUS) is used commonly by gynaecologists as a contraceptive and to treat menorrhagia. However, its efficacy has not been examined in women with inherited bleeding disorders. DESIGN: A prospective pilot study. SETTING: A teaching hospital in north London with a designated haemophilia centre. POPULATION: Female patients with a known inherited bleeding disorder. METHODS: Sixteen women with subjective and objective menorrhagia caused by inherited bleeding disorders (13 von Willebrand's Disease, two factor XI deficiency and one Hermansky-Pudlak syndrome), who had previously undergone unsuccessful medical treatment were followed up for nine months after LNG-IUS insertion. Bleeding was measured by pictorial chart and haemoglobin concentration. RESULTS: All women reported that their periods were improved, pictorial chart scores were lower and 56% became amenorrhoeic. None reported side effects. CONCLUSION: The LNG-IUS is well tolerated and effective and improves quality of life.
A new coagulation defect associated with a case of melanomatosis.
A marked abnormality of the intrinsic coagulation system was observed in a patient with melanomatosis and frank melanuria. With successful treatment of the tumour there was a parallel improvement in the clotting abnormality. This defect was shown to be a deficiency of factor XI together with a previously unrecognised factor. This is distinct from either Fletcher or Fitzgerald factors and appears to act between factors XI and X in the coagulation sequence.
Adhesion of human blood platelets to glass polymer surfaces. II. Demonstration of the presence of a natural platelet adhesion inhibitor in plasma and serum.
Adhesiveness of washed platelets resuspended in citrated plasma, serum, or several different media has been investigated. A method specific for quanititation of adhesion was used. Platelets suspended in saline of Tyrode's solution were found to be highly adhesive to glass, polyethylene, polyvinyl chloride, or Cuprophane. This adhesiveness of platelets to test surfaces decreased by nearly 50% when plasma was the suspension medium. When the suspension medium was serum, the decrease in adhesion was nearly 75%. Cohn fraction V also decreased the adhesiveness of platelets significantly, but highly purfied albumin had only a small effect. Several pharmacologic agents decreased platelet adhesiveness when added to platelets suspended in plasma or serum, but had negligible effect on the adhesiveness of platelets suspended in artificial media devoid of proteins. Normal washed platelets, when suspended in citrated plasma obtained from an afibrinogenemic donor or in normal serum, showed a significant decrease in adhesion compared to the same platelets suspended in normal citrated plasma. Addition of fibrinogen to afibrinogenemic plasma or normal serum restored the adhesiveness of platelets to normal levels. Normal platelets resuspended in plasma obtained from a thrombasthenic donor exhibited normal adhesiveness. These observations suggested that while fibrinogen promotes platelet adhesion, plasma or serum possess also an adhesion-inhibiting activity.
Activation and function of human Hageman factor. The role of high molecular weight kininogen and prekallikrein.
The activation and function of surface-bound Hageman factor in human plasma are dependent upon both high molecular weight (HMW) kininogen and prekallikrein. HMW kininogen does not affect the binding of Hageman factor to surfaces, but it enhances the function of surface-bound Hageman factor as assessed by its ability to activate prekallikrein and Factor XI. The initial conversion of prekallikrein to kallikrein by the surface-bound Hageman factor in the presence of HMW kininogen is followed by a rapid enzymatic activation of Hageman factor by kallikrein. The latter interaction is also facilitated by HMW kininogen. Kallikrein therefore functions as an activator of Hageman factor by a positive feedback mechanism and generates most of the activated Hageman factor during brief exposure of plasma to activating surfaces. HMW kininogen is a cofactor in the enzymatic activation of Hageman factor by kallikrein and it also augments the function of the activated Hageman factor generated. The stoichiometry of the Hagman factor interaction with HMW kininogen suggests that it enhances the activity of the active site of Hageman factor. Since HMW kininogen and prekallikrein circulate as a complex, HMW kininogen may also place the prekallikrein in an optimal position for its reciprocal interaction with Hageman factor to proceed. The surface appears to play a passive role upon which bound Hageman factor and the prekallikrein-HMW kininogen complex can interact.
Abnormal vaginal bleeding in adolescence as the presenting symptom of a bleeding diathesis.
Menorrhagia in adolescents may be the presenting sign of a systemic hemostatic disorder. The evaluation of adolescents with menorrhagia should include an assessment of the pelvic organs to exclude anatomic pathology, and if none is found the possibility of primary hematological abnormality should be considered. Initially, a thorough personal and family history of a bleeding tendency should be obtained. Thereafter, we suggest a number of basic "screening" clotting assays be performed. These should include a platelet count, prothrombin time, activated partial thromboplastin time, fibrinogen level and bleeding time. Abnormalities of any of these tests should then be further investigated using more specific clotting assays. The most common disorders reported to cause menorrhagia in adolescents are von Willebrand's disease, factor XI deficiency, and Glanzmann's thrombasthenia. General and specific therapeutic measures for treating these disorders are discussed.
Fibrinolysis and the contact system: a role for factor XI in the down-regulation of fibrinolysis.
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[Defects in the intrinsic pathway of the coagulation system].
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High prevalence of acquired von Willebrand's syndrome in patients with thyroid diseases undergoing thyroid surgery.
BACKGROUND AND OBJECTIVES: Various coagulation abnormalities occur in patients with thyroid diseases. These abnormalities range from subclinical laboratory findings to hemorrhage or thromboembolism. However, the prevalence of hemostatic abnormalities in patients with thyroid diseases is still unclear. DESIGN AND METHODS: Between January 1999 and December 2003, 1342 consecutive patients with various thyroid diseases who were candidates for thyroid surgery underwent preoperative screening of hemostatic parameters including prothrombin time, activated partial thromboplastin time and platelet-related hemostasis with the PFA-100 platelet-function analyzer. RESULTS: Thirty-nine patients (2.9%) had abnormalities of the coagulation screening tests. Of these, 35 patients had von Willebrand's disease (type 1 in 33 cases and type 2A in 2 cases), 2 patients had decreased platelet aggregability, and 2 patients had coagulation factor XI deficiency. As all patients with coagulation abnormalities responded to subcutaneous desmopressin injection (0.3 microg/Kg BW), this drug was successfully used as surgical prophylaxis. INTERPRETATION AND CONCLUSIONS: Up to 3% of patients with thyroid diseases undergoing thyroid surgery have coagulation abnormalities, in most cases resembling von Willebrand's disease. Coagulation screening tests are needed in order to identify those patients at increased risk of bleeding.
Prothrombin complex concentrates: preparation, properties, and clinical uses.
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