title: Comparison of two methods for measuring 25-OH vitamin D in the follow-up of patients after bilio-pancreatic diversion bariatric surgery.
abstract: OBJECTIVE
  Our objective was to compare the ECLIA from Roche versus the LC-MS/MS method for quantitation of serum 25-hydroxy-vitamin D in patients who have undergone bariatric surgery.
  
  
  METHODS
  Cross-sectional and correlational studies were performed on three different groups for the 25-OH-D levels quantitated by both methods. The control group of apparently healthy subjects was randomly selected in a clinical chemistry laboratory. Test groups were patients who had undergone bilio-pancreatic diversion (BPD) and were supplemented either with vitamin D2or with vitamin D3. The number of samples per group was established according to the CLSI recommendation protocol (EPO9-A2-IR).
  
  
  RESULTS
  The agreement of LC-MS/MS with the Roche method was acceptable in the apparently healthy subjects group and in the post-BPD D3-supplemented group with an average bias of -1.7% and -9.2%, respectively. However, this agreement was unacceptable in the post-BPD D2-supplemented group with an average bias of -45.3%. The LC-MS/MS enabled us to detect four patients who had excess vitamin D or poisoning with vitamin D for which it was necessary to stop the supplementation with vitamin D in the D2-supplemented group.
  
  
  CONCLUSIONS
  Despite the apparent good agreement between the Roche method and LC-MS/MS in the healthy subjects group and in the post-DBP D3-supplemented patient group, a considerable bias seems to exist, particularly in the presence of D2. The LC-MS/MS method is therefore the most accurate method to follow the vitamin D2-supplemented bariatric population.
authors.affiliation: Department of Clinical Biochemistry, CIUSSS-CHUS and CHUS Research Center, Faculty of Medicine & Health Sciences, Sherbrooke University, Sherbrooke, Quebec, Canada. Electronic address: ahlem.chouiali@usherbrooke.ca.
authors.forename: Ahlem
authors.initials: A
authors.lastname: Chouiali
authors.affiliation: Department of Clinical Biochemistry, CIUSSS-CHUS and CHUS Research Center, Faculty of Medicine & Health Sciences, Sherbrooke University, Sherbrooke, Quebec, Canada.
authors.forename: Pierre-Luc
authors.initials: PL
authors.lastname: Mallet
authors.affiliation: Department of Clinical Biochemistry, CIUSSS-CHUS and CHUS Research Center, Faculty of Medicine & Health Sciences, Sherbrooke University, Sherbrooke, Quebec, Canada.
authors.forename: Guy
authors.initials: G
authors.lastname: Fink
authors.affiliation: Department of Surgery, Faculty of Medicine & Health Sciences, Lava University l, Quebec, Quebec, Canada.
authors.forename: Simon
authors.initials: S
authors.lastname: Biron
authors.affiliation: Department of Medicine, CIUSSS-CHUS and CHUS Research Center, Faculty of Medicine & Health Sciences, Sherbrooke University, Sherbrooke, Quebec, Canada.
authors.forename: Marie-France
authors.initials: MF
authors.lastname: Langlois
mesh_terms: D015652:25-Hydroxyvitamin D 2 / Q000008:administration & dosage* / Q000097:blood; D000328:Adult; D000368:Aged; D050110:Bariatric Surgery; D015904:Biliopancreatic Diversion; D001774:Blood Chemical Analysis; D002112:Calcifediol / Q000008:administration & dosage* / Q000097:blood; D016022:Case-Control Studies; D003131:Combined Modality Therapy; D003430:Cross-Sectional Studies; D019587:Dietary Supplements; D005500:Follow-Up Studies; D006801:Humans; D008875:Middle Aged; D009765:Obesity / Q000097:blood* / Q000601:surgery; D015203:Reproducibility of Results; D053719:Tandem Mass Spectrometry
chemical_list: D015652:25-Hydroxyvitamin D 2; D002112:Calcifediol
keywords: 25-hydroxy-vitamin D; Bariatric surgery; Bilio-pancreatic diversion; ECLIA Roche; Tandem mass spectrometry