title: Multi-centre observational study of spurious hyperkalaemia due to EDTA contamination.
abstract: BACKGROUND
  A multi-centre observational study investigating the prevalence of spurious hyperkalaemia due to potassium ethylenediaminetetraacetic acid (kEDTA) contamination.
  
  
  METHODS
  Serum EDTA was measured in anonymised serum samples with a serum potassium > 6.0 mmol/L collected over a one month period in five different hospital laboratories. Two of the participating laboratories routinely screen all hyperkalaemic samples for EDTA contamination.
  
  
  RESULTS
  EDTA contamination was present in 4.1% (range 1.2%-6.7%) of hyperkalaemic samples. In three laboratories, without routine EDTA screening, 50% "EDTA contaminated" were identified by laboratory staff, the remaining 50% samples were undetected and reported as genuine hyperkalaemia. In these laboratories, EDTA was not measurable in 2 samples reported as "EDTA contaminated".
  
  
  CONCLUSIONS
  Spurious hyperkalaemia due to kEDTA contamination is relatively common. Education regarding correct blood collection technique offers the best strategy in preventing EDTA sample contamination. Gross kEDTA contamination is easily identified by laboratory staff in samples with marked unexpected hyperkalaemia and hypocalcaemia. Spurious hyperkalaemia due to modest kEDTA contamination may only be confidently detected by measurement of serum EDTA.
authors.affiliation: Department of Clinical Chemistry, New Cross Hospital, Wolverhampton, West Midlands, UK. Michael.cornes@nhs.net
authors.forename: Michael P
authors.initials: MP
authors.lastname: Cornes
authors.forename: Fraser
authors.initials: F
authors.lastname: Davidson
authors.forename: Lucy
authors.initials: L
authors.lastname: Darwin
authors.forename: Chris
authors.initials: C
authors.lastname: Gay
authors.forename: Mark
authors.initials: M
authors.lastname: Redpath
authors.forename: Jenna L
authors.initials: JL
authors.lastname: Waldron
authors.forename: Clare
authors.initials: C
authors.lastname: Ford
authors.forename: Rousseau
authors.initials: R
authors.lastname: Gama
mesh_terms: D001793:Blood Preservation / Q000379:methods*; D001800:Blood Specimen Collection; D003430:Cross-Sectional Studies; D004340:Drug Contamination; D004492:Edetic Acid / Q000097:blood*; D005189:False Positive Reactions; D006801:Humans; D006947:Hyperkalemia / Q000097:blood*; D011188:Potassium / Q000097:blood
chemical_list: D004492:Edetic Acid; D011188:Potassium