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Laboratory coagulation assays
Published in John Edward Boland, David W. M. Muller, Interventional Cardiology and Cardiac Catheterisation, 2019
The tests available in the Multiplate system are: ADPtest. Measures platelet aggregation in the presence of adenosine diphosphate (ADP). Sensitive to ADP receptor defects and P2Y12 inhibitors such as clopiodgrel and prasugrel.ADPtest HS. A high-sensitivity measure of the ADP P2Y12 pathway through addition of prostaglandin E2.ASPItest. Measures platelet aggregation in the presence of arachidonic acid. Sensitive to aspirin.TRAPtest. Measures platelet aggregation in the presence of a thrombin receptor activating peptide (platelet PAR1 thrombin receptor). Antiplatelet agents such as aspirin and clopidogrel have little effect on this assay.COLtest. Measures platelet aggregation in the presence of collagen. Sensitive to collagen receptor defects.RISTOtest high and low. Measures platelet aggregation/agglutination in the presence of high and low concentrations of ristocetin. Used to diagnose von Willebrand disease.
SBA Answers and Explanations
Published in Vivian A. Elwell, Jonathan M. Fishman, Rajat Chowdhury, SBAs for the MRCS Part A, 2018
Vivian A. Elwell, Jonathan M. Fishman, Rajat Chowdhury
Von Willebrand disease is the most common hereditary bleeding disorder. It is caused by an abnormality, either quantitative or qualitative, of the von Willebrand factor, which is a large multimeric glycoprotein that functions as the carrier protein for factor VIII. Von Willebrand factor is also required for normal platelet adhesion. Von Willebrand disease can be classified into 3 main types: Type 1 accounts for 70–80 per cent of cases. It is characterized by a partial quantitative decrease of qualitatively normal von Willebrand factor and factor VIII. An individual with type 1 disease generally has mild clinical symptoms, and this type is usually inherited as an autosomal dominant trait; however, penetrance may widely vary in a single family.Type 2 accounts for 15–20 per cent of cases. It is a variant with primarily qualitative defects of von Willebrand factor. It can be either autosomal dominant or autosomal recessive.Type 3 is the most severe form. In the homozygous patient, it is characterized by marked deficiencies of both von Willebrand factor and factor VIII in the plasma, and the absence of von Willebrand factor from both platelets and endothelial cells. It is characterized by severe clinical bleeding and is inherited as an autosomal recessive trait.
Haemostasis: Normal Physiology, Disorders of Haemostasis and Thrombosis
Published in John C Watkinson, Raymond W Clarke, Louise Jayne Clark, Adam J Donne, R James A England, Hisham M Mehanna, Gerald William McGarry, Sean Carrie, Basic Sciences Endocrine Surgery Rhinology, 2018
Elizabeth Jones, Russell David Keenan
Von Willebrand disease is an inherited bleeding disorder. It can be seen with autosomal dominant or recessive inheritance. It is categorized into three types. The most common is type 1. This is usually a relatively mild partial quantitative deficiency, that is, a reduced amount of a normal von Willebrand factor (vWF). Type 2 is split into further groups but all involve abnormal vWF, usually with reduced function. Type 3 is near absence of vWF that leads to a severe bleeding phenotype very similar to severe haemophilia A.
An evaluation of von Willebrand factor (recombinant) therapy for adult patients living with severe type 3 von Willebrand disease
Published in Expert Review of Hematology, 2023
John M. Hancock, Miguel A. Escobar
The vast majority of patients in the NCT02973087 rVWF prophylaxis trial had severe type 3 VWD with an average number ~6.5 spontaneous bleeds per year prior to starting on rVWF prophylaxis. Given the potentially improved efficacy and similar safety profile of rVWF prophylaxis compared to plasma-derived products, and the theoretical decreased (albeit small) risk of viral infection from plasma-derived products, it is possible that rVWF prophylaxis may represent a new standard of care for patients with type 3 VWD with a severe bleeding phenotype. More data is needed to show the efficacy and safety of rVWF used for prophylaxis for patients with type 1 and type 2 VWD with a severe bleeding phenotype. More recently, the new Guidelines on the Management of von Willebrand disease have been published and endorsed by ASH/ISTH/WFH/NHF. These guidelines are in favor of a secondary long-term prophylaxis with a von Willebrand Factor concentrate over no long-term prophylaxis for those patients with severe and frequent bleeding episodes [1].
Sudden-onset haemolacria in an adolescent girl
Published in Paediatrics and International Child Health, 2021
Ayla Akca Caglar, Halise Akca, Funda Kurt, Leman Akcan Yildiz, Pinar Nalcacioglu, Onur Buyukkoc, Emine Dibek Misirlioglu
To determine the cause, laboratory investigations were undertaken. A complete haemogram, prothrombin time, activated partial thromboplastin time, bleeding time and thyroid function test were normal. Laboratory tests for von Willebrand disease—von Willebrand factor ristocetin cofactor assay, von Willebrand factor antigen assay and Factor VIII activity assay—were also within normal limits. Computed tomography (CT) scan of the head and orbit to rule out a paranasal sinus-related pathology demonstrated mucosal thickening in the left fronto-ethmoidal recess at the base of the frontal sinus and polypoid mucosal thickening in the maxillary sinuses bilaterally. These findings did not explain the cause of the haemolacria, and the patient was diagnosed with idiopathic haemolacria. She was given empirical therapy with high-dose vitamin C (500 mg daily), prophylactic iron therapy and psychological support. In the first month, haemolacria occurred several times a day and each episode lasted for 10 minutes. During follow-up, there was spontaneous reduction in the frequency of symptoms. At the end of 4 months, the episodes occurred approximately once or twice a week and lasted for 3–5 minutes.
Overcoming the challenges of treating hemophilia in resource-limited nations: a focus on medication access and adherence
Published in Expert Review of Hematology, 2021
Kanjaksha Ghosh, Kinjalka Ghosh
Here the RLN should create a portfolio of different factor concentrates to suit their pocket. A small amount of extended half-life product may be included and about 10–20% of the budgeted fund for hemophilia care may be kept aside for management of patients with inhibitors, as unlike many developed countries prevalence of inhibitors in severe hemophilia patients are still low. Virally inactivated intermediate purity plasma derived product may still treat a large number of PWH in these countries in a cost effective manner. Some of these products can also be used to treat Von-willebrand disease patients. In many RLN countries other inherited so called rare bleeding disorders are not so rare and for many of these conditions concentrates are either not available or is difficult to include in the portfolio of these countries hence development of good transfusion service in these countries is a prerequisite. Safe plasma and cryoprecipitate from these services can be used to treat rare inherited plasmatic defect of blood coagulation. These blood banks can also provide required FFP and Cryoprecipitate to develop plasma fractionation centers in their own country or get the product contract fractionated from many giant fractionation centers in the world having spare capacity.