Misura della proteina S e della resistenza alla proteina C attivata. Risultati della Valutazione Esterna di Qualità (VEQ)-CISMEL*

Background. One of the aims of the External Quality Assurance Scheme (EQAS) is to provide information useful to standardize laboratory methods and to help choosing the most appropriate laboratory strategy to investigate clinical conditions. Methods. We looked at the results coming from the EQAS in coagulation organized by the CISMEL group in three different exercises where participants analyzed three well characterized plasmas for protein S and activated protein C resistance. Results. Three consecutive exercises showed that the functional anticoagulant assay for protein S is affected by the presence of the factor V Leiden mutation and that the method for the measurement of activated protein C resistance based on prediluiton of test plasma in factor V deficient plasma is highly specific for factor V Leiden. Conclusions. EQAS exercises carried out across the country with samples unknown to the participants confirm two important findings that may be used to design a diagnostic strategy for the investigation of patients with thrombophilia.