Multicenter evaluation of light transmission platelet aggregation reagents: communication from the ISTH SSC Subcommittee on Platelet Physiology.

Background: Light transmission aggregation (LTA) is used widely by the clinical and research communities. Although it is a gold standard, there is a lack of interlaboratory harmonization.

Objectives: The primary objective was to assess whether sources of activators (mainly adenosine diphosphate [ADP], collagen, arachidonic acid, epinephrine, and thrombin receptor activating peptide6) and ristocetin contribute to poor LTA reproducibility.

Ristocetin-Induced Platelet Aggregation (RIPA) and RIPA Mixing Studies.

Ristocetin-induced platelet aggregation (RIPA) is used as an in vitro test to determine the presence and integrity of the platelet glycoprotein (GP) Ibα-V-IX complex and von Willebrand factor (VWF) interaction and is usually performed using platelet-rich plasma (PRP). Impairment in the response of VWF/GPIbα-V-IX is measured with reference to several established concentrations of ristocetin and may indicate defects in VWF or in GPIbα-V-IX function. RIPA-based mixing studies comprise an additional approach to testing this interaction to help define whether defects identified by RIPA lie in VWF or in GPIbα-V-IX.

Light transmission aggregometry.

Laboratory testing of platelet function is essential for the diagnosis of several congenital and acquired platelet disorders. Moreover, it is increasingly being utilized to monitor the efficacy of antiplatelet therapy. Light transmission platelet aggregation is the most useful in vitro test of platelet function currently available, and it is still the gold standard to detect platelet disorders and to initiate a more precise characterization.

Von Willebrand disease in children: diagnosis and management of a pediatric cohort in one single center in Argentina.

Clinical and laboratory data of children with von Willebrand disease (VWD) types have been derived from retrospective studies and small case series. This article reports on the clinical and laboratory data of a large pediatric cohort in one single Argentinian center. The biological and clinical responses to desmopressin and replacement therapies are also described.

Frequency of platelet type versus type 2B von Willebrand disease. An international registry-based study.

Less than 50 patients are reported with platelet type von Willebrand disease (PT-VWD) worldwide. Several reports have discussed the diagnostic challenge of this disease versus the closely similar disorder type 2B VWD. However, no systematic study has evaluated this dilemma globally.

Prospective study of low-dose ristocetin-induced platelet aggregation to identify type 2B von Willebrand disease (VWD) and platelet-type VWD in children.

Type 2B von Willebrand disease (VWD2B) and platelet-type von Willebrand disease (PT-VWD) are rare bleeding disorders characterised by an increased ristocetin-induced platelet aggregation (RIPA) at low dose of ristocetin. It was the objective of this study to detect children with VWD2B and PT-VWD using RIPA at low dose of ristocetin (0.5 mg/ml) in the screening evaluation of bleeding disorders, and to analyse the phenotypic data along with the molecular findings.

Arterial ischemic stroke and cerebral venous thrombosis in children: a 12-year Argentinean registry.

Over a 12-year period, 112 consecutive children with arterial ischemic stroke (AIS) and 38 children with cerebral venous thrombosis (CVT) were prospectively recruited at a single pediatric center in Argentina. One or more underlying clinical conditions were identified in most patients (55%) with AIS and in almost all patients with CVT. Inherited and/or acquired prothrombotic disorders were detected in 17% of the patients with AIS and in 34% of the children with CVT.

Factor V Leiden and prothrombin gene G20210A mutation in children with cerebral thromboembolism.

We investigated whether there is an association between factor V Leiden (FVL) and/or prothrombin gene G20210A mutation (PT20210A) and cerebral thromboembolism in a pediatric Argentinean population. From May 1992 to January 2002, 44 consecutive children with arterial ischemic stroke (AIS) and 23 children with cerebral sinovenous thrombosis (SVT) were prospectively studied at a single center. The prevalence of both mutations was compared with a 102 age-matched controls.

Factor V Leiden and prothrombin gene G20210A mutation in children with venous thromboembolism.

To determine whether factor V Leiden (FVL) and/or prothrombin gene G20210A mutation (PT20210A) are risk factors for venous thromboembolism (VTE) in Argentinean children. One hundred and thirty consecutive children with VTE were prospectively assisted at a single centre. Blood samples were available from 110 of them for detailed haematological analysis.