A multicenter laboratory assessment of a new automated chemiluminescent assay for ADAMTS13 activity.

Background: Thrombotic thrombocytopenic purpura (TTP) is a rare but potentially fatal disorder caused by ADAMTS13 (a disintegrin and metalloproteinase with a thrombospondin type 1 motif, member 13) deficiency. Prompt identification/exclusion of TTP can thus be facilitated by rapid ADAMTS13 testing. The most commonly utilized (enzyme-linked immunosorbent assay [ELISA]-based) assay takes several hours to perform and so does not generally permit rapid testing.

A multicentre assessment of contemporary laboratory assays for heparin induced thrombocytopenia.

Heparin induced thrombocytopenia (HIT) is a rare but potentially fatal complication of heparin therapy. In some patients, HIT causes platelet activation and thrombosis (sometimes abbreviated HITT), which leads to adverse clinical sequalae ('pathological HIT'). The likelihood of HIT is initially assessed clinically, typically using a scoring system, of which the 4T score is that most utilised.

The effect of dabigatran on the activated partial thromboplastin time and thrombin time as determined by the Hemoclot thrombin inhibitor assay in patient plasma samples.

Dabigatran is an oral direct thrombin inhibitor that does not require routine laboratory monitoring. However, an assessment of its anticoagulant effect in certain clinical settings is desirable. We examined the relationship between dabigatran levels, as determined by the Hemoclot thrombin inhibitor assay (HTI), the thrombin time (TT) and the activated partial thromboplastin time (aPTT) using different reagents.

Factor XIII assays.

Factor XIII (FXIII) deficiency is a rare cause of bleeding and pregnancy loss that is easily treated with plasma products. Reliable assays for FXIII are necessary not only for the diagnosis of deficiency state but also to guide prophylaxis and replacement therapy in patients during times of increased risk. Diagnostic tests for FXIII activity whilst not technically demanding have a number of pitfalls including limited sensitivity and overestimation of activity at the lower end.

Relationship of waist and hip circumference with coagulation and fibrinolysis in postmenopausal women.

The contribution of obesity to the occurrence of cardiovascular events may not be wholly related to its influence on traditional risk factors. Coagulation and fibrinolysis may also influence cardiovascular risk, but the relationship of adiposity with these processes is unclear. The aim of the present study was to investigate the relationships of BMI (body mass index), waist circumference, hip circumference and WHR (waist-to-hip ratio) with VIIc (factor VII activity), plasma markers of thrombin generation [F1+2 (prothrombin fragment 1+2)], fibrin formation [SF (soluble fibrin)] and fibrin turnover (D-dimer), and PAI-1 (plasminogen activator inhibitor-1; a marker of fibrinolytic inhibitory capacity).

Comparison of effects of pravastatin and hormone therapy on soluble P-selectin and platelet P-selectin expression in postmenopausal hypercholesterolemic women.

Objective: Recent trials have suggested an adverse early effect on cardiovascular risk of hormone therapy (HT) in postmenopausal women, an effect which could be due to an increase in arterial thrombosis via platelet activation. We examined the effect of HT on platelet surface expression of P-selectin, a marker of platelet activation, and plasma levels of soluble P-selectin, also believed to be a marker of platelet activation, and compared these effects with pravastatin, a drug proven to reduce cardiovascular events and reported to decrease both platelet and soluble P-selectin.

Methods: Surface expression of platelet P-selectin, soluble P-selectin and fasting lipids were measured at baseline and 6 months in a randomized, double-blind study of postmenopausal hypercholesterolemic women comparing low-dose combined HT (1mg estradiol + 0.

Dietary soy containing phytoestrogens does not activate the hemostatic system in postmenopausal women.

The soybean is rich in isoflavone phytoestrogens, which are ligands for estrogen receptors, but it is unknown whether soy/phytoestrogens have similar procoagulant effects to estrogen. In this randomized double-blind trial, 40 healthy postmenopausal women of age 50-75 yr received soy protein isolate (40 g soy protein, 118 mg isoflavones) (n = 19) or casein placebo (n = 21). Plasma markers of coagulation, fibrinolysis, and endothelial dysfunction were measured at baseline and 3 months.

Chronic threshold testing of implantable cardioverter defibrillators does not increase coagulation activity or platelet activation.

It is unknown if the brief periods of circulatory statis occurring with induction of VF during DFT testing in patients with an ICD activate blood coagulation processes. To address this question, coagulation activity and platelet activation were measured in peripheral venous blood samples obtained from 12 patients undergoing DFT testing under general anesthesia, 3 (n = 11) or 6 months (n = 1) after ICD implantation for recurrent ventricular arrhythmias. Five patients were anticoagulated with warfarin and two to six episodes of VF (median five) were induced per patient.