title: Serum insulin-like growth factor-I (IGF-I) reference ranges for chemiluminescence assay in childhood and adolescence. Data from a population of in- and out-patients.
abstract: BACKGROUND
  Insulin-like growth factor I (IGF-I) measurement is widely used for the diagnosis of disorders of GH secretion and sensitivity, and for monitoring of both GH and IGF-I replacement therapies. However, the lack of appropriate reference values obtained from large and representative samples undermines its practical utility.
  
  
  OBJECTIVE
  To establish IGF-I reference values for a commonly used enzyme-labeled chemiluminescent immunometric assay in a large population of children aged 0 to 18 years.
  
  
  METHODS
  Cross-sectional analysis of serum IGF-I levels from samples collected in the two major Italian Children's Hospitals.
  
  
  METHODS
  IGF-I was measured using a solid-phase, enzyme-labeled chemiluminescent immunometric assay in 24403 children (50.6% girls) aged 0 to 18 years. Quantile regression coupled to multivariable fractional polynomials was used to produce age- and sex-specific reference values.
  
  
  METHODS
  Age- and sex-specific IGF-I reference values.
  
  
  CONCLUSIONS
  Reference values for immunometric assay of IGF-I were produced in a large sample of children and adolescents. Prediction equations were provided to automatize their calculations.
authors.affiliation: Clinical Epidemiology Unit, Liver Research Center, Basovizza and Fondazione IRCCS Cà Granda, Ospedale Maggiore Policlinico, Milano, Italy.
authors.forename: G
authors.initials: G
authors.lastname: Bedogni
authors.forename: G
authors.initials: G
authors.lastname: Giannone
authors.forename: M
authors.initials: M
authors.lastname: Maghnie
authors.forename: C
authors.initials: C
authors.lastname: Giacomozzi
authors.forename: N
authors.initials: N
authors.lastname: Di Iorgi
authors.forename: S
authors.initials: S
authors.lastname: Pedicelli
authors.forename: E
authors.initials: E
authors.lastname: Peschiaroli
authors.forename: G
authors.initials: G
authors.lastname: Melioli
authors.forename: M
authors.initials: M
authors.lastname: Muraca
authors.forename: M
authors.initials: M
authors.lastname: Cappa
authors.forename: S
authors.initials: S
authors.lastname: Cianfarani
mesh_terms: D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D007297:Inpatients; D007334:Insulin-Like Growth Factor I / Q000378:metabolism*; D007558:Italy; D008163:Luminescent Measurements / Q000379:methods; D008297:Male; D010045:Outpatients; D012016:Reference Values; D012044:Regression Analysis
chemical_list: D007334:Insulin-Like Growth Factor I