title: Establishment of trimester-specific thyroid stimulating hormone and free thyroxine reference interval in pregnant Chinese women using the Beckman Coulter UniCel™ DxI 600.
abstract: BACKGROUND
  Thyroid-stimulating hormone (TSH) and free thyroxine (FT4) reference intervals are essential for screening and diagnosing thyroid dysfunction during pregnancy. The aim of this study was to establish method- and trimester-specific TSH and FT4 reference intervals in pregnant Chinese women using the Beckman Coulter UniCel™ DxI 600.
  
  
  METHODS
  A cross-sectional dataset analysis was performed. A total of 3507 participants were recruited, and 2743 were eligible for analysis to set reference intervals. TSH, FT4, and thyroid peroxidase antibody (TPOAb) levels were analyzed with the Beckman Coulter UniCel™ DxI 600 Access® immunoassay system. Ranges between the 2.5th and 97.5th percentiles were defined as reference intervals for TSH and FT4.
  
  
  RESULTS
  The calculated reference intervals for the first, second, and third trimesters were TSH: 0.06-3.13, 0.07-4.13 and 0.15-5.02 mIU/L, respectively, and FT4: 8.72-15.22, 7.10-13.55 and 6.16-12.03 pmol/L, respectively.
  
  
  CONCLUSIONS
  Our reference intervals for TSH and FT4 are distinct from the ranges reported in the DxI 600 instruction manual and previously reported data, confirming the importance of method-specific reference intervals.
authors.forename: Jing
authors.initials: J
authors.lastname: Zhang
authors.forename: Wei
authors.initials: W
authors.lastname: Li
authors.forename: Qiao-Bin
authors.initials: QB
authors.lastname: Chen
authors.forename: Li-Yi
authors.initials: LY
authors.lastname: Liu
authors.forename: Wei
authors.initials: W
authors.lastname: Zhang
authors.forename: Meng-Ying
authors.initials: MY
authors.lastname: Liu
authors.forename: Yi-Ting
authors.initials: YT
authors.lastname: Wang
authors.forename: Wen-Ya
authors.initials: WY
authors.lastname: Li
authors.forename: Li-Zhen
authors.initials: LZ
authors.lastname: Zeng
mesh_terms: D000293:Adolescent; D000328:Adult; D001774:Blood Chemical Analysis / Q000592:standards*; D005260:Female; D006801:Humans; D007118:Immunoassay; D011247:Pregnancy; D011264:Pregnancy Trimesters; D012016:Reference Values; D013972:Thyrotropin / Q000097:blood*; D013974:Thyroxine / Q000097:blood*; D055815:Young Adult
chemical_list: D013972:Thyrotropin; D013974:Thyroxine