Description:
<jats:title>Summary</jats:title><jats:p>We investigated the relationship between platelet function analyzer (PFA‐100<jats:sup>TM</jats:sup>) closure times (CT) and bleeding time (BT), platelet aggregation (PA) induced by ADP, arachidonic acid, and collagen, blood cell counts, and von Willebrand factor (VWF) in 120 well‐characterised healthy individuals. Pre‐analytical and analytical conditions were standardised comprehensively. In a substantial number of cases the differences between duplicate measurements exceeded 15%. The reference range (5th and 95th percentiles) for CT with the collagen/epinephrine (CEPI) and the collagen/ADP (CADP) cartridge was 93–223 s and 64–117 s respectively. Re‐examination of 11 individuals with CEPI‐CT above the 95th percentile revealed considerable batch‐to‐batch variation of CEPI‐CT. Males had significantly longer CADP than females (<jats:italic>P</jats:italic> = 0·002). CEPI and CADP‐CT measured <jats:sc>pm</jats:sc> were significantly longer than corresponding values determined <jats:sc>am</jats:sc> (<jats:italic>P</jats:italic> = 0·003 and <jats:italic>P</jats:italic> < 0·0001 respectively). Blood group O was associated with greater CEPI and CADP‐CT and lower VWF levels compared with non‐O blood groups (<jats:italic>P</jats:italic> = 0·008, <jats:italic>P</jats:italic> = 0·0003 and <jats:italic>P</jats:italic> < 0·0001 respectively). Linear regression analysis revealed association between CEPI‐CT, CADP‐CT and VWF (<jats:italic>P</jats:italic> < 0·0001), but no relationship was found between CT and BT or between CT and PA. We conclude that VWF plasma levels modulate PFA‐100<jats:sup>TM</jats:sup> CT to a greater extent than platelet function. Establishment of reliable reference ranges and careful standardisation of pre‐analytical and analytical conditions is a prerequisite for obtaining reliable PFA‐100<jats:sup>TM</jats:sup> results. Duplicate measurements are necessary.</jats:p>