title: Growth hormone secretion decreases with age in paediatric Prader-Willi syndrome.
abstract: OBJECTIVE
  Growth hormone deficiency is a common feature of Prader-Willi syndrome; however, biochemical deficiency is not uniformly demonstrated. Criteria for GH treatment in paediatric PWS vary with some countries requiring documentation of biochemical GH deficiency. Data regarding the significance of age in the interpretation of GH stimulation test results, particularly in infants, are lacking. We aimed to assess age-related trends in the prevalence of biochemical GH deficiency in infants and children with PWS.
  
  
  METHODS
  A retrospective chart review was conducted. Data from children with Prader-Willi syndrome that had GH stimulation tests performed at the Hospital for Sick Children in Toronto between the years 2000 and 2012 were collected.
  
  
  METHODS
  Charts of 47 children 0·4-15·5 years of age with PWS that had GH stimulation tests were reviewed.
  
  
  METHODS
  Biochemical GH status in relation to age and body mass index.
  
  
  RESULTS
  Thirty-two of 47 patients (68%) were biochemically GH deficient. GH deficiency was significantly associated with older age (r = 0·45, P = 0·02) and higher body-mass-index z-score (r = 0·45, P = 0·02). Biochemical GH deficiency was less prevalent up to 18 months of age (3/11 27%) compared with older children (29/36 [81%]; P = 0·001). A higher prevalence of GH deficiency was also detected in obese patients (14/16 [88%]) compared with nonobese patients (18/31 [58%]; P = 0·04).
  
  
  CONCLUSIONS
  The utility of performing GH stimulation tests as an indication of GH status under 18 months of age in Prader-Willi syndrome is questionable. If performed, results should be carefully interpreted in the context of age.
authors.affiliation: Division of Endocrinology, The Hospital for Sick Children, University of Toronto, Toronto, ON, Canada.
authors.forename: M
authors.initials: M
authors.lastname: Cohen
authors.affiliation: Division of Endocrinology, The Hospital for Sick Children, University of Toronto, Toronto, ON, Canada.
authors.forename: J
authors.initials: J
authors.lastname: Harrington
authors.affiliation: Division of Respiratory Medicine, The Hospital for Sick Children, University of Toronto, Toronto, ON, Canada.
authors.forename: I
authors.initials: I
authors.lastname: Narang
authors.affiliation: Division of Endocrinology, The Hospital for Sick Children, University of Toronto, Toronto, ON, Canada.
authors.forename: J
authors.initials: J
authors.lastname: Hamilton
mesh_terms: D000293:Adolescent; D000367:Age Factors; D015992:Body Mass Index; D002648:Child; D002675:Child, Preschool; D005260:Female; D019382:Human Growth Hormone / Q000172:deficiency* / Q000627:therapeutic use; D006801:Humans; D007223:Infant; D008297:Male; D009864:Ontario; D063766:Pediatric Obesity; D011218:Prader-Willi Syndrome / Q000097:blood* / Q000188:drug therapy*; D015995:Prevalence; D012189:Retrospective Studies
chemical_list: D019382:Human Growth Hormone