title: Cellular content in plasma of Becton-Dickinson lithium-heparin tubes: cause of unreliable results in the IFCC-recommended lactate dehydrogenase method.
abstract: BACKGROUND
  Measurement of lactate dehydrogenase (LDH) with the International Federation of Clinical Chemistry (IFCC)-recommended method in plasma was reported unreliable with primary evacuated lithium-heparin tubes from Becton-Dickinson, despite adequate removal of platelets from the plasma by optimized sample preparation. In this study, the composition of the top layer of the heparin plasma was investigated in relation to these duplicate errors.
  
  
  METHODS
  Microscopic evaluation of cytospin preparations of the top layer of the plasma was compared with the difference between duplicates in the IFCC-recommended LDH assay using a Hitachi 911 analyser.
  
  
  RESULTS
  Duplicate errors could not be explained by the presence of one of the individual cell types. In 16 samples with cellular aggregates absent, three did show duplicate errors; all three had a moderate amount of red blood cells present.
  
  
  CONCLUSIONS
  The presence of cellular aggregates in the top layer of the plasma was the main determinant for the occurrence of the high frequency of duplicate errors in the IFCC-recommended LDH method.
authors.affiliation: Department of Clinical Chemistry, Stichting Klinisch Chemisch Laboratorium, Leeuwarden, The Netherlands. a.j.bakker@kcl.znb.nl
authors.forename: Andries J
authors.initials: AJ
authors.lastname: Bakker
authors.forename: Anneke
authors.initials: A
authors.lastname: Bakker
authors.forename: Hennie
authors.initials: H
authors.lastname: Renting-Wiering
mesh_terms: D001773:Blood Cells; D001800:Blood Specimen Collection / Q000295:instrumentation* / Q000379:methods; D003951:Diagnostic Errors; D006493:Heparin; D006801:Humans; D007770:L-Lactate Dehydrogenase / Q000097:blood*; D008094:Lithium; D015203:Reproducibility of Results
chemical_list: D006493:Heparin; D008094:Lithium; D007770:L-Lactate Dehydrogenase