title: Precision of the magnesium determination in mononuclear blood cells and erythrocytes.
abstract: OBJECTIVE
  Establishing the analytical variation and reproducibility of the intracellular magnesium (Mg) assay in mononuclear blood cells (MBC) and erythrocytes (RBC).
  
  
  METHODS
  We assessed the analytical variation of the several determination steps, and the reproducibility for the complete intracellular Mg-assay (combination of preanalytical, analytical, and biological variation). The influence of platelets was determined by comparing Mg concentrations obtained from heparinized blood and defibrinated blood.
  
  
  RESULTS
  Coefficients of variation of the several determination steps used in the MBC- and RBC-assay were < or = 5.4%. The overall analytical variation was 5.0-6.8%, and reproducibility of the complete Mg-assay 11.6-14.0%. Mg measurements in MBC (expressed as fmol/cell) obtained from heparinized blood showed significantly higher values than those obtained from defibrinated blood.
  
  
  CONCLUSIONS
  This is the first study to describe in detail reproducibility data for the individual steps in the overall procedure to measure intracellular magnesium. It is shown that results obtained in daily practice should be interpreted with care. Moreover, the removal of platelets is essential in the determination of Mg in MBC.
authors.affiliation: Department of Clinical Chemistry, Academic Medical Center, Amsterdam, The Netherlands.
authors.forename: H J
authors.initials: HJ
authors.lastname: Huijgen
authors.forename: H E
authors.initials: HE
authors.lastname: van Ingen
authors.forename: R
authors.initials: R
authors.lastname: Sanders
authors.forename: F R
authors.initials: FR
authors.lastname: Gaffar
authors.forename: J
authors.initials: J
authors.lastname: Oosting
authors.forename: G T
authors.initials: GT
authors.lastname: Sanders
mesh_terms: D001800:Blood Specimen Collection; D004912:Erythrocytes / Q000737:chemistry*; D006493:Heparin; D006801:Humans; D008274:Magnesium / Q000097:blood*; D009000:Monocytes / Q000737:chemistry*; D015203:Reproducibility of Results
chemical_list: D006493:Heparin; D008274:Magnesium