title: Comparison of automated 25-OH vitamin D immunoassays with liquid chromatography isotope dilution tandem mass spectrometry.
abstract: BACKGROUND
  Comparing two fully automated 25-OH-D immunoassays with a validated liquid chromatography isotope dilution tandem mass spectrometry (LC-IDMS/MS) method in human serum samples.
  
  
  METHODS
  180 samples were analyzed with the Liaison TOTAL Vitamin D, the IDS-iSYS 25-Hydroxy Vitamin D, and a validated LC-IDMS/MS 25-OH D method.
  
  
  RESULTS
  The Liaison method mean +/- standard deviation (SD) was 64.3 +/- 23.5 nmol/L; the IDS-iSYS 70.1 +/- 27.0 nmol/L, and the LC-IDMS/MS 68.9 +/- 24.6 nmol/L. The correlation coefficient (r) between the Liaison and LC-IDMS/MS was 0.723, and the r between the IDS-iSYS and LC-IDMS/MS was 0.799. When the samples were grouped by females and males, the r between the Liaison and LC-IDMS/MS was 0.680 and 0.846, being 0.781 and 0.863 between the IDS-iSYS and LC-IDMS/MS, respectively. With the Passing-Bablok analysis, only the IDS-iSYS gave equivalent results to LC-IDMS/MS.
  
  
  CONCLUSIONS
  The automated 25-OH-D immunoassays were in clinically good overall agreement with the LC-IDMS/MS method.
authors.affiliation: Institute of Diagnostics, Department of Clinical Chemistry, University of Oulu, Finland.
authors.forename: Marja-Kaisa
authors.initials: MK
authors.lastname: Koivula
authors.forename: Ursula
authors.initials: U
authors.lastname: Turpeinen
authors.forename: Päivi
authors.initials: P
authors.lastname: Laitinen
authors.forename: Juha
authors.initials: J
authors.lastname: Risteli
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D002675:Child, Preschool; D002853:Chromatography, Liquid / Q000379:methods*; D005260:Female; D006801:Humans; D007118:Immunoassay / Q000379:methods*; D007223:Infant; D008297:Male; D008875:Middle Aged; D053719:Tandem Mass Spectrometry / Q000379:methods*; D014807:Vitamin D / Q000031:analogs & derivatives* / Q000097:blood; D055815:Young Adult
chemical_list: D014807:Vitamin D; C104450:25-hydroxyvitamin D