title: Cut-off limits of the peak GH response to stimulation tests for the diagnosis of GH deficiency in children and adolescents: study in patients with organic GHD.
abstract: OBJECTIVE
  The diagnosis of GH deficiency (GHD) in children and adolescents is established when GH concentrations fail to reach an arbitrary cut-off level after at least two provocative tests. The objective of the study was to define the optimal GH cut-offs to provocative tests in children and adolescents.
  
  
  METHODS
  Retrospective study in 372 subjects who underwent evaluation of GH secretion. GH and IGF-I were measured by chemiluminescence assay in all samples. Receiver operating characteristic (ROC) analysis was used to evaluate the optimal GH cut-offs and the diagnostic accuracy of provocative tests.
  
  
  METHODS
  Seventy four patients with organic GHD (GH peak <10μg/L after two provocative tests) and 298 control subjects (GH response >10μg/L to at least one test) were included in the study. The provocative tests used were arginine, insulin tolerance test (ITT) and clonidine. Diagnostic criteria based on cut-offs identified by ROC analysis (best pair of values for sensitivity and specificity) were evaluated for each test individually and for each test combined with IGF-I SDS.
  
  
  RESULTS
  The optimal GH cut-off for arginine resulted 6.5μg/L, 5.1μg/L for ITT and 6.8μg/L for clonidine. IGF-I SDS has low accuracy in diagnosing GHD (AUC=0.85). The combination of the results of provocative tests with IGF-I concentrations increased the specificity.
  
  
  CONCLUSIONS
  The results of the ROC analysis showed that the cut-off limits which discriminate between normal and GHD are lower than those commonly employed. IGF-I is characterized by low diagnostic accuracy.
authors.affiliation: SSD Endocrinologia PediatricaOspedale Pediatrico Microcitemico "A. Cao", Cagliari, Italy.
authors.forename: Chiara
authors.initials: C
authors.lastname: Guzzetti
authors.affiliation: SSD Endocrinologia PediatricaOspedale Pediatrico Microcitemico "A. Cao", Cagliari, Italy.
authors.forename: Anastasia
authors.initials: A
authors.lastname: Ibba
authors.affiliation: SSD Endocrinologia PediatricaOspedale Pediatrico Microcitemico "A. Cao", Cagliari, Italy.
authors.forename: Sabrina
authors.initials: S
authors.lastname: Pilia
authors.affiliation: Ospedale Generale RegionaleBolzano, Italy.
authors.forename: Nadia
authors.initials: N
authors.lastname: Beltrami
authors.affiliation: Clinica Pediatrica, Istituto Giannina Gaslini, Universitá di GenovaGenova, Italy.
authors.forename: Natascia
authors.initials: N
authors.lastname: Di Iorgi
authors.affiliation: Universitá di BolognaOspedale S.Orsola-Malpighi, Bologna, Italy.
authors.forename: Alessandra
authors.initials: A
authors.lastname: Rollo
authors.affiliation: Clinica Pediatrica, Istituto Giannina Gaslini, Universitá di GenovaGenova, Italy.
authors.forename: Nadia
authors.initials: N
authors.lastname: Fratangeli
authors.affiliation: Ospedale Generale RegionaleBolzano, Italy.
authors.forename: Giorgio
authors.initials: G
authors.lastname: Radetti
authors.affiliation: Universitá di BolognaOspedale S.Orsola-Malpighi, Bologna, Italy.
authors.forename: Stefano
authors.initials: S
authors.lastname: Zucchini
authors.affiliation: Clinica Pediatrica, Istituto Giannina Gaslini, Universitá di GenovaGenova, Italy.
authors.forename: Mohamad
authors.initials: M
authors.lastname: Maghnie
authors.affiliation: UOC di Endocrinologia e DiabetologiaOspedale Pediatrico Bambino Gesú IRCCS, Roma, Italy.
authors.forename: Marco
authors.initials: M
authors.lastname: Cappa
authors.affiliation: SSD Endocrinologia PediatricaOspedale Pediatrico Microcitemico "A. Cao", Cagliari, Italy sandro.loche@aob.it.
authors.forename: Sandro
authors.initials: S
authors.lastname: Loche
mesh_terms: D000293:Adolescent; D001120:Arginine; D002648:Child; D003000:Clonidine; D005260:Female; D019382:Human Growth Hormone / Q000172:deficiency*; D006801:Humans; D007018:Hypopituitarism / Q000175:diagnosis*; D007328:Insulin; D007334:Insulin-Like Growth Factor I / Q000032:analysis*; D008297:Male; D012189:Retrospective Studies; D012680:Sensitivity and Specificity
chemical_list: D007328:Insulin; D019382:Human Growth Hormone; D007334:Insulin-Like Growth Factor I; D001120:Arginine; D003000:Clonidine