title: Contamination of lithium heparin blood by K2-ethylenediaminetetraacetic acid (EDTA): an experimental evaluation.
abstract: BACKGROUND
  The contamination of serum or lithium heparin blood with ethylenediaminetetraacetic acid (EDTA) salts may affect accuracy of some critical analytes and jeopardize patient safety. The aim of this study was to evaluate the effect of lithium heparin sample contamination with different amounts of K2EDTA.
  
  
  METHODS
  Fifteen volunteers were enrolled among the laboratory staff. Two lithium heparin tubes and one K2EDTA tube were collected from each subject. The lithium-heparin tubes of each subject were pooled and divided in 5 aliquots. The whole blood of K2EDTA tube was then added in scalar amount to autologous heparinised aliquots, to obtained different degrees of K2EDTA blood volume contamination (0%; 5%; 13%; 29%; 43%). The following clinical chemistry parameters were then measured in centrifuged aliquots: alanine aminotranspherase (ALT), bilirubin (total), calcium, chloride, creatinine, iron, lactate dehydrogenase (LD), lipase, magnesium, phosphate, potassium, sodium.
  
  
  RESULTS
  A significant variation starting from 5% K2EDTA contamination was observed for calcium, chloride, iron, LD, magnesium (all decreased) and potassium (increased). The variation of phosphate and sodium (both increased) was significant after 13% and 29% K2EDTA contamination, respectively. The values of ALT, bilirubin, creatinine and lipase remained unchanged up to 43% K2EDTA contamination. When variations were compared with desirable quality specifications, the bias was significant for calcium, chloride, LD, magnesium and potassium (from 5% K2EDTA contamination), sodium, phosphate and iron (from 29% K2EDTA contamination).
  
  
  CONCLUSIONS
  The concentration of calcium, magnesium, potassium, chloride and LD appears to be dramatically biased by even modest K2EDTA contamination (i.e., 5%). The values of iron, phosphate, and sodium are still reliable up to 29% K2EDTA contamination, whereas ALT, bilirubin, creatinine and lipase appear overall less vulnerable towards K2EDTA contamination.
authors.affiliation: Laboratory of Clinical Biochemistry, Department of Life and Reproduction Sciences, University of Verona, Verona, Italy ; Post-Graduate Program of Pharmaceutical Sciences, Department of Clinical Analyses, Federal University of Parana, Curitiba, Parana, Brazil.
authors.forename: Gabriel
authors.initials: G
authors.lastname: Lima-Oliveira
authors.affiliation: Laboratory of Clinical Biochemistry, Department of Life and Reproduction Sciences, University of Verona, Verona, Italy.
authors.forename: Gian Luca
authors.initials: GL
authors.lastname: Salvagno
authors.affiliation: Laboratory of Clinical Biochemistry, Department of Life and Reproduction Sciences, University of Verona, Verona, Italy.
authors.forename: Elisa
authors.initials: E
authors.lastname: Danese
authors.affiliation: Laboratory of Clinical Biochemistry, Department of Life and Reproduction Sciences, University of Verona, Verona, Italy.
authors.forename: Giorgio
authors.initials: G
authors.lastname: Brocco
authors.affiliation: Laboratory of Clinical Biochemistry, Department of Life and Reproduction Sciences, University of Verona, Verona, Italy ; Post-Graduate Program of Pharmaceutical Sciences, Department of Clinical Analyses, Federal University of Parana, Curitiba, Parana, Brazil.
authors.forename: Gian Cesare
authors.initials: GC
authors.lastname: Guidi
authors.affiliation: Laboratory of Clinical Chemistry and Hematology, Academic Hospital of Parma, Parma, Italy.
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Lippi
mesh_terms: D000328:Adult; D000925:Anticoagulants / Q000737:chemistry / Q000592:standards; D001774:Blood Chemical Analysis; D001800:Blood Specimen Collection / Q000295:instrumentation / Q000379:methods / Q000592:standards*; D004340:Drug Contamination / Q000706:statistics & numerical data*; D004492:Edetic Acid / Q000032:analysis* / Q000097:blood; D004866:Equipment Contamination / Q000706:statistics & numerical data*; D005260:Female; D006493:Heparin / Q000737:chemistry; D006801:Humans; D008094:Lithium / Q000737:chemistry; D008297:Male; D008875:Middle Aged; D061214:Patient Safety; D017749:Total Quality Management
chemical_list: D000925:Anticoagulants; D006493:Heparin; D008094:Lithium; D004492:Edetic Acid
keywords: EDTA; contamination; patient safety; preanalytical phase; preanalytical variability; total quality management