title: Reference intervals for free T3 and free T4 in Pakistani euthyroid patients: effect of age and gender on thyroid function.
abstract: OBJECTIVE
  To establish reference intervals for Free Triiodothyronine (FT3) and Free Thyroxine (FT4) in euthyroid subjects and to assess the effect of age and gender on FT3 and FT4.
  
  
  METHODS
  Cross-sectional, analytical study.
  
  
  METHODS
  Institute of Nuclear Medicine and Oncology (INMOL), Lahore, from January 2009 to April 2011.
  
  
  METHODS
  FT3 and FT4 were measured in 852 euthyroid patients. Those with previous thyroid surgery, on thyroidrelated medication and severe non-thyroid illness were excluded.
  
  
  RESULTS
  There were 215 males and 637 females with mean age of 46 years. The reference intervals, revealed by this study, for FT3 and FT4 were 2.80 - 5.39 pmol/L and 11.9 - 22.2 pmol/L respectively. The mean difference between gender groups and age groups was found statistically significant for FT3 (gender: p < 0.001; age: p < 0.001) but statistically insignificant for FT4 (gender: p=0.147; age: p=0.201).
  
  
  CONCLUSIONS
  There was no effect of gender and age on FT3 and FT4. The age with serum FT3 and FT4 significantly negatively correlated but this correlation was stronger for FT3 as compared to FT4 levels. Reference intervals of FT3 and FT4 for male (2.99 - 5.63 pmol/L, 12.3 - 22.6 pmol/L) and female (2.77 - 5.29 pmol/L, 11.7 - 22.1 pmol/L) respectively are suggested.
authors.affiliation: Institute of Nuclear Medicine and Oncology (INMOL), Lahore.
authors.forename: Raana
authors.initials: R
authors.lastname: Abbas
authors.affiliation: Institute of Nuclear Medicine and Oncology (INMOL), Lahore.
authors.forename: Hafiz Ghulam
authors.initials: HG
authors.lastname: Abbas
authors.affiliation: Institute of Nuclear Medicine and Oncology (INMOL), Lahore.
authors.forename: Abubaker
authors.initials: A
authors.lastname: Shahid
authors.affiliation: College of Statistical and Actuarial Sciences, University of the Punjab, Lahore.
authors.forename: Sohail
authors.initials: S
authors.lastname: Chand
authors.affiliation: Medical Student, Lahore College for Women University, Lahore.
authors.forename: Sara
authors.initials: S
authors.lastname: Nawaz
mesh_terms: D000293:Adolescent; D000328:Adult; D017677:Age Distribution; D000368:Aged; D002648:Child; D002675:Child, Preschool; D003430:Cross-Sectional Studies; D005260:Female; D006044:Goiter, Nodular / Q000097:blood; D006403:Hematologic Tests; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D008875:Middle Aged; D011863:Radioimmunoassay; D012016:Reference Values; D017678:Sex Distribution; D013960:Thyroid Function Tests / Q000592:standards* / Q000706:statistics & numerical data; D013961:Thyroid Gland / Q000502:physiology*; D013974:Thyroxine / Q000097:blood*; D014284:Triiodothyronine / Q000097:blood*; D055815:Young Adult
chemical_list: D014284:Triiodothyronine; D013974:Thyroxine