title: Pre-analytical variation of some haematological quantities.
abstract: BACKGROUND
  It is customary to assume that pre-analytical variation is negligible if all pre-analytical sources of variation have been standardised. The aim of this study was to quantify the pre-analytical variation of some haematological quantities frequently measured in clinical laboratories.
  
  
  METHODS
  The experimental design considers different sources of pre-analytical variation that usually occur day-to-day for samples from patients.
  
  
  RESULTS
  The results demonstrate that for concentrations of erythrocytes, haemoglobin, leukocytes, neutrophilocytes (segmented) and lymphocytes, and for the volume fraction of erythrocytes ("packed cell volume") in blood, the pre-analytical variance is not negligible.
  
  
  CONCLUSIONS
  We suggest that these variances should be taken into account when estimating the uncertainty of measurement for patient results.
authors.affiliation: Laboratori Clínic, IDIBELL--Hospital Universitari de Bellvitge, L'Hospitalet de Llobregat, Catalonia, Spain.
authors.forename: Mariona
authors.initials: M
authors.lastname: García-Panyella
authors.forename: Ariadna
authors.initials: A
authors.lastname: Padró-Miquel
authors.forename: Dolors
authors.initials: D
authors.lastname: Dot-Bach
authors.forename: Xavier
authors.initials: X
authors.lastname: Fuentes-Arderiu
mesh_terms: D000704:Analysis of Variance; D016477:Artifacts; D006400:Hematocrit; D006403:Hematologic Tests / Q000379:methods; D006801:Humans; D035501:Uncertainty