The impact of pre-analytical variable, type of anticoagulant and time delay, on the measurement of mean platelet volume.

Introduction Platelets are essential in primary haemostasis and a low or high platelet count is a significant risk factor for bleeding or thrombosis. Platelet volume indices, like mean platelet volume (MPV), platelet distribution width and platelet cell ratio, are a group of parameters which are derived from routine blood counts. The MPV is the most attractive for research in clinical settings and is routinely measured by automated hematology analyzers using impedance or optical fluorescence method (Leader et al 2012). Platelet size, measured by MPV, has been proposed to become marker of platelet activity, as it was found to correlate with in vitro platelet activation (Riedl et al 2014). It has been recently shown that MPV is highly correlated with cardiovascular events. Patients with acute myocardial infarction (AMI) have a higher MPV than those without AMI (Chu et al 2010; Klovaite et al 2011). A higher MPV is associated with cardiovascular risk factors like diabetes mellitus, dislipidemia, hypertension, smoking and obesity. Also, MPV was found increased during acute non-lacunar ischemic stroke and venous thrombosis (Muscari et al 2008; Brækkan et al 2010). Many studies recognized that MPV have potential for clinical utility especially in hematology (inherited macrothrombocytopenia) and in vascular medicine (Gohda et al 2007). There are conflicting data on the relevance of MPV to distinguish between thrombocytosis from Ph-MPN and reactive thrombocytosis (Leader et al 2012). Song et al found an increased MPV on essential thrombocytemia (ET) than in reactive thrombocytosis (Song et al 2009), whereas others have found a lower MPV in myeloproliferative neoplasms (Sehayek et al 1988) or the same (Small & Bettigole 1981). Classic Philadelphia-negative chronic myeloproliferative neoplasms (Ph-MPN) , according to the World Health Organization (WHO) classification, include polycythemia vera (PV), essential thrombocythemia (ET) and primary myelofibrosis (PMF) and are characterized by an incidence of arterial and venous thrombosis (Falanga & Marchetti 2012). Numerous platelet abnormalities, both quantitative and qualitative, have been identified in PV and ET patients, but not clearly linked to thrombotic events (Landolfi et al 2008). The clinical utility of MPV is significantly limited by variability of measurement and lack of standardization. If the MPV is Abstract. Introduction: Mean platelet volume (MPV), parameter provided by automated haematology analysers could become a useful biomarker to detect, in vivo, platelet activation. Unfortunately, MPV is affected by time, storage conditions and the nature of anticoagulants. Our study was designed to determinate the influence of anticoagulant and time delay from blood collection on MPV measurements. Materials and methods: Fasting venous blood samples were collected from 102 patients patients diagnosed with Ph-MPN (Philadelphia-negative myeloproliferative neoplasms) and from 57 healthy subjects into sterile tubes with K2EDTA and sodium citrate 3.2%. Blood cell counts including MPV were assessed through the impedance method on Sysmex XS 1000i at 30 minutes and 2 hours after blood collection. Results: In our study we found a significant difference between MPV values measured in blood collected into tubs with K2EDTA compared with those containing sodium citrate 3.2% at 30 minutes and 2 hours (p<0.001). MPV from citrated samples revealed significantly smaller MPV. The values of MPV measured in tubs with K2EDTA at different times, 30 minutes and two hours, revealed a significant difference (p<0.001). We did not notice this difference from tubs containing sodium citrate as anticoagulant. Conclusion: In our study we demonstrated that time and type of anticoagulants influence the MPV values, measured by impedance based method. Result from the present study show that storage of blood samples in EDTA based anticoagulant resulted in a progressive increase in the MPV and make EDTA not suitable as anticoagulant for the research on platelet function.