title: Reference ranges for thyroid hormones in normal Italian children and adolescents and overweight adolescents.
abstract: BACKGROUND
  As thyroid hormones are essential for normal pubertal growth and sexual development, TSH, free T₃ (FT₃) and free T₄ (FT₄) levels undergo progressive modification during childhood and puberty.
  
  
  OBJECTIVE
  To establish thyroid hormone reference ranges in pre-pubertal children, pubertal adolescents, and adults and to evaluate any differences in thyroid function between overweight and normalweight pubertal subjects.
  
  
  METHODS
  Chemiluminescent microparticle immunoassay was used to analyze TSH, FT₃ and FT₄ concentrations in serum samples from 508 children and adolescents aged 6 to 18 yr and 100 healthy adults aged 30 to 60 yr, and from 68 overweight pubertal adolescents. As data were not normally distributed, we compared them through non-parametric tests for independent samples and the reference ranges were assumed to lie between the 2.5th and 97.5th percentile.
  
  
  RESULTS
  We found a progressive and significant reduction in TSH, FT₃, and FT₄ levels in the three groups with increasing age. TSH levels were significantly higher in overweight patients than in the normal-weight group, but there were no significant differences for FT₃ or FT₄.
  
  
  CONCLUSIONS
  This study revealed significant differences in levels of thyroid hormone between different age groups and allowed us to establish normal reference ranges for pre-pubertal children between 0.87-5.19 mIU/l for TSH, 4.75-8.59 pmol/l for FT₃, and 13.09-20.61 pmol/l for FT₄, and for pubertal adolescents between 0.76- 4.51 mIU/l for TSH, 4.26-8.46 pmol/l for FT₃ and 10.94-19.09 pmol/l for FT₄.
authors.affiliation: Section of Medical Pathophysiology and Endocrinology, Department of Experimental Medicine, Sapienza University of Rome, Viale del Policlinico 155, 00161 Rome, Italy. antonio.radicioni@uniroma1.it
authors.forename: A F
authors.initials: AF
authors.lastname: Radicioni
authors.forename: N
authors.initials: N
authors.lastname: Tahani
authors.forename: M
authors.initials: M
authors.lastname: Spaziani
authors.forename: A
authors.initials: A
authors.lastname: Anzuini
authors.forename: C
authors.initials: C
authors.lastname: Piccheri
authors.forename: A
authors.initials: A
authors.lastname: Semeraro
authors.forename: L
authors.initials: L
authors.lastname: Tarani
authors.forename: A
authors.initials: A
authors.lastname: Lenzi
mesh_terms: D000293:Adolescent; D041923:Adolescent Development; D000328:Adult; D015992:Body Mass Index; D002648:Child; D002657:Child Development; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D050177:Overweight / Q000097:blood*; D012016:Reference Values; D012384:Rome; D013972:Thyrotropin / Q000097:blood*; D013974:Thyroxine / Q000097:blood*; D014284:Triiodothyronine / Q000097:blood*
chemical_list: D014284:Triiodothyronine; D013972:Thyrotropin; D013974:Thyroxine