title: The use of insulin-like growth factor 1 reference values for the diagnosis of growth hormone deficiency in prepubertal children.
abstract: OBJECTIVE
  This study was done to determine whether the use of reference values obtained in children with idiopathic short stature (ISS) improved the clinical value of serum insulin-like growth factor I (IGF-1) as a tool for diagnosing GH deficiency (GHD) in prepubertal children.
  
  
  METHODS
  Serum IGF-1 was measured with a new IRMA kit (IGFI-RIA CT, Cis Bio, Gif sur Yvette, France) in 168 prepubertal normal children and in prepubertal children with ISS (n = 68), organic GHD due to a craniopharyngioma (oGHD, n = 15) and permanent idiopathic GHD (iGHD, n = 28).
  
  
  RESULTS
  IGF-1 was lower (P < 0.001) in iGHD than in either ISS or oGHD and was below the fifth percentile of the normal range in 29/68 ISS (43%), 8/15 oGHD (53%) and 28/28 (100%) iGHD patients. Three oGHD (20%) and two iGHD (7%) patients had a serum IGF-1 below the fifth percentile of the normal group but above the fifth percentile of the ISS group. Thus, a serum IGF-1 below the fifth percentile of the normal group distinguished between normal children and iGHD with 100% sensitivity, between normal and oGHD with 53% sensitivity and between normal and all GHD (idiopathic + organic) with 84% sensitivity; the overall specificity was only 57%. Conversely, a serum IGF-1 below the fifth percentile of the ISS population distinguished between ISS and iGHD with 93% sensitivity, between ISS and oGHD with 33% sensitivity and between ISS and all GHD with 72% sensitivity; the overall specificity was then 95%.
  
  
  CONCLUSIONS
  A serum IGF-1 within the normal range virtually excludes idiopathic GHD but does not rule out organic GHD, whereas an IGF-1 below the ISS range is strongly in favour of GHD, after exclusion of poor nutritional status and/or liver disease. An IGF-1 below the normal range but in the idiopathic short stature range gives no definitive conclusion even when it is associated with a low GH peak. Thus, whereas reference values obtained in normal children must be used to interpret serum IGF-1 in short prepubertal children, reference data obtained in idiopathic short stature children should also be taken into account.
authors.affiliation: Department of Physiology, Hôpital Necker-Enfants Malades, Université R Descartes, Paris, France.
authors.forename: L
authors.initials: L
authors.lastname: Bussières
authors.forename: J C
authors.initials: JC
authors.lastname: Souberbielle
authors.forename: G
authors.initials: G
authors.lastname: Pinto
authors.forename: L
authors.initials: L
authors.lastname: Adan
authors.forename: M
authors.initials: M
authors.lastname: Noel
authors.forename: R
authors.initials: R
authors.lastname: Brauner
mesh_terms: D002648:Child; D002675:Child, Preschool; D003397:Craniopharyngioma / Q000097:blood* / Q000150:complications; D005260:Female; D006130:Growth Disorders / Q000097:blood* / Q000209:etiology; D013006:Growth Hormone / Q000097:blood / Q000172:deficiency*; D006801:Humans; D007223:Infant; D007334:Insulin-Like Growth Factor I / Q000032:analysis*; D008297:Male; D010911:Pituitary Neoplasms / Q000097:blood* / Q000150:complications; D011237:Predictive Value of Tests; D012016:Reference Values; D012680:Sensitivity and Specificity
chemical_list: D007334:Insulin-Like Growth Factor I; D013006:Growth Hormone