title: Establishment of reference intervals for serum thyroid-stimulating hormone, free and total thyroxine, and free and total triiodothyronine for the Beckman Coulter DxI-800 analyzers by indirect method using data obtained from Chinese population in Zhejiang Province, China.
abstract: BACKGROUND
  In order to establish suitable reference intervals of thyroid-stimulating hormone (TSH), free (unbound) T4 (FT4), free triiodothyronine (FT3), total thyroxine (T4), and total triiodothyronine (T3) for the patients collected in Zhejiang, China, an indirect method was developed using the data from the people presented for routine health check-up.
  
  
  METHODS
  Fifteen thousand nine hundred and fifty-six person's results were reviewed. Box-Cox or Case Rank was used to transform the data to normal distribution. Tukey and Box-Plot methods were used to exclude the outliers. Nonparametric method was used to establish the reference intervals following the EP28-A3c guideline. Pearson correlation was used to evaluate the correlation between hormone levels and age, while Mann-Whitney U test was employed for quantification of concentration differences on the people who are younger and older than 50 years old.
  
  
  RESULTS
  Reference intervals were 0.66-4.95 mIU/L (TSH), 8.97-14.71 pmol/L (FT4), 3.75-5.81 pmol/L (FT3), 73.45-138.93 nmol/L (total T4), and 1.24-2.18 nmol/L (total T3) in male; conversely, reference intervals for female were 0.72-5.84 mIU/L (TSH), 8.62-14.35 pmol/L (FT4), 3.59-5.56 pmol/L (FT3), 73.45-138.93 nmol/L (total T4), and 1.20-2.10 nmol/L (total T3). FT4, FT3, and total T3 levels in male and FT4 level in female had an inverse correlation with age. Total T4 and TSH levels in female were directly correlated. Significant differences in these hormones were also found between younger and older than 50 years old except FT3 in female.
  
  
  CONCLUSIONS
  Indirect method can be applied for establishment of reference intervals for TSH, FT4, FT3, total T4, and total T3. The reference intervals are narrower than those previously established. Age factor should also be considered.
authors.affiliation: Hangzhou Prenatal Diagnosis (Screening) Center, Hangzhou Maternity and Child Health Care Hospital, Hangzhou, China.
authors.forename: Yan
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Key Laboratory of Tumor Molecular Diagnosis and Individualized Medicine of Zhejiang Province, Hangzhou, China.|Clinical Laboratory Center of Zhejiang Provincial People's Hospital, Hangzhou, China.
authors.forename: Yu-Xia
authors.initials: YX
authors.lastname: Zhang
authors.affiliation: Key Laboratory of Tumor Molecular Diagnosis and Individualized Medicine of Zhejiang Province, Hangzhou, China.|Clinical Laboratory Center of Zhejiang Provincial People's Hospital, Hangzhou, China.
authors.forename: Yong-Lie
authors.initials: YL
authors.lastname: Zhou
authors.affiliation: Key Laboratory of Tumor Molecular Diagnosis and Individualized Medicine of Zhejiang Province, Hangzhou, China.|Clinical Laboratory Center of Zhejiang Provincial People's Hospital, Hangzhou, China.
authors.forename: Jun
authors.initials: J
authors.lastname: Xia
mesh_terms: D000328:Adult; D001774:Blood Chemical Analysis / Q000592:standards*; D002681:China; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012016:Reference Values; D013960:Thyroid Function Tests / Q000592:standards*; D013972:Thyrotropin / Q000097:blood*; D013974:Thyroxine / Q000097:blood*; D014284:Triiodothyronine / Q000097:blood*
chemical_list: D014284:Triiodothyronine; D013972:Thyrotropin; D013974:Thyroxine
keywords: indirect method; reference intervals; thyroid hormone