title: Establishment of reference serum insulin-like growth factor-I and insulin-like growth factor binding protein-3 levels of Tunisian children during childhood and adolescence.
abstract: BACKGROUND
  The aim of the present study is to establish age- and sex-related reference ranges of serum IGF-I and IGF binding protein-3 (IGFBP-3) levels in a pattern of Tunisian children.
  
  
  METHODS
  Two hundred healthy Tunisian children (103 boys and 97 girls), aged between 6 and 16 yr, were considered in the study.
  
  
  RESULTS
  Mean serum levels of IGF-I and IGFBP-3 are observed to be higher in girls compared to boys of the same age interval. However, these differences were statistically significant only in pubertal ages (11-14 yr) for IGF-I and in pre-pubertal ages (6-10 yr) for IGFBP- 3 (p<0.05). Steeper variations in IGF-I concentrations were obtained earlier in girls than in boys (11-12 vs 12-13 yr, Tanner stage 3-4). Peak of IGF-I levels are observed at almost the same age interval (12-14 yr). IGFBP-3 levels significantly increased at steeper variations of IGF-I for both sexes followed by steady values.
  
  
  CONCLUSIONS
  Variations of IGF-I and IGFBP- 3 with the considered parameters (sex, age, and puberty stage), which concord with previous studies on various populations, emphasize the importance of locally established reference levels to construct a SD score prediction model. Establishment of reference serum IGF-I and IGFBP-3 ranges during childhood and adolescence in Tunisian subjects can help to enhance the diagnostic efficiency of IGF-I and IGFBP-3 in evaluating growth disorders in our population.
authors.affiliation: Laboratory of Physiology and Functional Explorations, Faculty of Medicine Ibn El-Jazzar, Tunisia. sonia_sfar@yahoo.fr
authors.forename: S
authors.initials: S
authors.lastname: Sfar
authors.forename: M
authors.initials: M
authors.lastname: Zaouali Ajina
authors.forename: S
authors.initials: S
authors.lastname: Ben Mdalla
authors.forename: A
authors.initials: A
authors.lastname: Baklouti
authors.forename: H
authors.initials: H
authors.lastname: Knani
authors.forename: Z
authors.initials: Z
authors.lastname: Tabka
authors.forename: A
authors.initials: A
authors.lastname: Zbidi
mesh_terms: D000293:Adolescent; D000367:Age Factors; D002648:Child; D005260:Female; D006801:Humans; D018972:Insulin-Like Growth Factor Binding Protein 3 / Q000097:blood*; D007334:Insulin-Like Growth Factor I / Q000378:metabolism*; D008297:Male; D011627:Puberty / Q000502:physiology; D012016:Reference Values; D012737:Sex Factors; D014416:Tunisia
chemical_list: D018972:Insulin-Like Growth Factor Binding Protein 3; D007334:Insulin-Like Growth Factor I