title: 25OHD analogues and vacuum blood collection tubes dramatically affect the accuracy of automated immunoassays.
abstract: Variations in vitamin D quantification methods are large, and influences of vitamin D analogues and blood collection methods have not been systematically examined. We evaluated the effects of vitamin D analogues 25OHD2 and 3-epi 25OHD3 and blood collection methods on vitamin D measurement, using five immunoassay systems and liquid chromatography-tandem mass spectrometry (LC-MS/MS). Serum samples (332) were selected from routine vitamin D assay requests, including samples with or without 25OHD2 or 3-epi 25OHD3, and analysed using various immunoassay systems. In samples with no 25OHD2 or 3-epi 25OHD3, all immunoassays correlated well with LC-MS/MS. However, the Siemens system produced a large positive mean bias of 12.5 ng/mL and a poor Kappa value when using tubes with clot activator and gel separator. When 25OHD2 or 3-epi 25OHD3 was present, correlations and clinical agreement decreased for all immunoassays. Serum 25OHD in VACUETTE tubes with gel and clot activator, as measured by the Siemens system, produced significantly higher values than did samples collected in VACUETTE tubes with no additives. Bias decreased and clinical agreement improved significantly when using tubes with no additives. In conclusion, most automated immunoassays showed acceptable correlation and agreement with LC-MS/MS; however, 25OHD analogues and blood collection tubes dramatically affected accuracy.
authors.affiliation: Department of Clinical Laboratory, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, Beijing 100730, China.
authors.forename: Songlin
authors.initials: S
authors.lastname: Yu
authors.affiliation: Department of Clinical Laboratory, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, Beijing 100730, China.
authors.forename: Xinqi
authors.initials: X
authors.lastname: Cheng
authors.affiliation: Department of Clinical Laboratory, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, Beijing 100730, China.
authors.forename: Huiling
authors.initials: H
authors.lastname: Fang
authors.affiliation: Department of Clinical Laboratory, China-Japan Hospital, Beijing 100029, China.
authors.forename: Ruiping
authors.initials: R
authors.lastname: Zhang
authors.affiliation: Department of Clinical Laboratory, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, Beijing 100730, China.
authors.forename: Jianhua
authors.initials: J
authors.lastname: Han
authors.affiliation: Department of Clinical Laboratory, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, Beijing 100730, China.
authors.forename: Xuzhen
authors.initials: X
authors.lastname: Qin
authors.affiliation: Department of Clinical Laboratory, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, Beijing 100730, China.
authors.forename: Qian
authors.initials: Q
authors.lastname: Cheng
authors.affiliation: Department of Clinical Laboratory, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, Beijing 100730, China.
authors.forename: Wei
authors.initials: W
authors.lastname: Su
authors.affiliation: Department of Clinical Laboratory, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, Beijing 100730, China.
authors.forename: Li'an
authors.initials: L
authors.lastname: Hou
authors.affiliation: Department of Clinical Laboratory, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, Beijing 100730, China.
authors.forename: Liangyu
authors.initials: L
authors.lastname: Xia
authors.affiliation: Department of Clinical Laboratory, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, Beijing 100730, China.
authors.forename: Ling
authors.initials: L
authors.lastname: Qiu
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D057205:Automation, Laboratory; D001800:Blood Specimen Collection / Q000295:instrumentation* / Q000379:methods*; D002112:Calcifediol / Q000009:adverse effects / Q000031:analogs & derivatives* / Q000097:blood*; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007118:Immunoassay / Q000379:methods / Q000592:standards*; D007223:Infant; D008297:Male; D013058:Mass Spectrometry; D008875:Middle Aged; D015203:Reproducibility of Results; D055815:Young Adult
chemical_list: D002112:Calcifediol