title: Evaluation of the GHRH-arginine retest for young adolescents with childhood-onset GH deficiency.
abstract: OBJECTIVE
  Retesting of adolescents with childhood-onset GH deficiency (GHD) is recommended, but age-related reference data are scarce. We aimed to establish a cut-off value for the GHRH-arginine test (GHRH+ARG) at the typical age of retesting at near-adult height.
  
  
  METHODS
  We retrospectively studied 149 patients (108 males) with childhood-onset GHD aged 16.8 ± 1.7 years (mean ± SD) with a BMI of 20.9 ± 3.5 kg/m(2) who had received GHRH+ARG in one single center during 8 consecutive years. Based on the IGF-I serum concentration falling below -2 SDS when off GH, 22 patients suffered from severe GHD of adulthood while 122 were GH sufficient. Five patients could not be determined definitively. GH and IGF-I were measured by in-house RIAs. IGF-I values were transformed into age-related SDS values. ROC-analysis was used to determine the cut-off value.
  
  
  RESULTS
  For GHRH+ARG, a cut-off limit of 15.9 ng/ml had the highest pair of sensitivity (91%) and specificity (88%). GH peaks of the patients with a normal BMI between -1 and 0 SDS were higher than those with a high BMI >1 SDS (p<0.01).
  
  
  CONCLUSIONS
  When retesting adolescents at near-adult height for severe GHD of adulthood, a GH value of <15.9 ng/ml in GHRH+ARG is discriminatory with good accuracy. Conversion factors for other GH assays in use are provided. A rational decision for or against the continuation of GH therapy into adulthood can be made based on the clinical history of the patient and the combination of the GHRH+ARG retest result and the IGF-I serum concentrations when off GH.
authors.affiliation: University Children's Hospital, Pediatric Endocrinology, Hoppe-Seyler-Str.1, 72076 Tübingen, Germany.
authors.forename: Laura
authors.initials: L
authors.lastname: Dreismann
authors.affiliation: University Children's Hospital, Pediatric Endocrinology, Hoppe-Seyler-Str.1, 72076 Tübingen, Germany.
authors.forename: Roland
authors.initials: R
authors.lastname: Schweizer
authors.affiliation: Department of Clinical Epidemiology and Applied Biometry, University of Tübingen, Silcherstraße 5, 72076 Tübingen, Germany.
authors.forename: Gunnar
authors.initials: G
authors.lastname: Blumenstock
authors.affiliation: University Children's Hospital, Pediatric Endocrinology, Hoppe-Seyler-Str.1, 72076 Tübingen, Germany.
authors.forename: Karin
authors.initials: K
authors.lastname: Weber
authors.affiliation: University Children's Hospital, Pediatric Endocrinology, Hoppe-Seyler-Str.1, 72076 Tübingen, Germany. Electronic address: gerhard.binder@med.uni-tuebingen.de.
authors.forename: Gerhard
authors.initials: G
authors.lastname: Binder
mesh_terms: D000293:Adolescent; D000328:Adult; D001120:Arginine / Q000032:analysis*; D002648:Child; D003940:Diagnostic Techniques, Endocrine; D005260:Female; D005500:Follow-Up Studies; D013007:Growth Hormone-Releasing Hormone / Q000032:analysis*; D019382:Human Growth Hormone / Q000172:deficiency*; D006801:Humans; D007018:Hypopituitarism / Q000175:diagnosis*; D007334:Insulin-Like Growth Factor I / Q000032:analysis*; D008297:Male; D011379:Prognosis; D012372:ROC Curve; D012189:Retrospective Studies
chemical_list: D019382:Human Growth Hormone; D007334:Insulin-Like Growth Factor I; D013007:Growth Hormone-Releasing Hormone; D001120:Arginine
keywords: BMI; Childhood-onset GHD; GH cut-off; GHRH–arginine test; IGF-I