title: Effect of body mass index on the growth hormone response to clonidine stimulation testing in children with short stature.
abstract: OBJECTIVE
  An inverse relationship has been shown between body mass index (BMI) and the peak growth hormone (GH) response to stimulation in adults and in children with short stature. This relation is observed even within a normal range of BMI. The aim of this study was to investigate the effect of BMI on the GH response to clonidine in a large number of children with short stature.
  
  
  METHODS
  We conducted a retrospective study on the GH response to clonidine in a single centre.
  
  
  METHODS
  We studied 202 children with short stature (135 M and 67 F) who underwent clonidine testing from 2007 to 2009.
  
  
  RESULTS
  One hundred and twenty-eight patients had a GH peak >10 μg/l. In univariate regression analysis, the peak GH after clonidine was negatively correlated with BMI-standard deviation score (BMI-SDS) and positively correlated with height velocity-SDS and IGF-I-SDS. Only the relationship between peak GH and BMI-SDS remained significant in children with a BMI-SDS from -2 to +2. In the multivariate stepwise regression analysis, BMI-SDS and IGF-I-SDS were the only significant variables in the entire cohort, explaining 19·5% of the variance in peak GH. When only subjects with BMI-SDS between -2·0 and +2·0 were included in the analysis (n = 173), BMI-SDS alone explained 21·4% of the variability in peak GH. The number of patients who failed the clonidine test increased with increasing BMI-SDS.
  
  
  CONCLUSIONS
  BMI affects the GH response to clonidine in children with short stature and should be considered when interpreting the results to the stimulation test.
authors.affiliation: Servizio di Endocrinologia Pediatrica, Ospedale Microcitemico, ASL Cagliari, Cagliari, Italy. sandroloche@asl8cagliari.it
authors.forename: Sandro
authors.initials: S
authors.lastname: Loche
authors.forename: Chiara
authors.initials: C
authors.lastname: Guzzetti
authors.forename: Sabrina
authors.initials: S
authors.lastname: Pilia
authors.forename: Anastasia
authors.initials: A
authors.lastname: Ibba
authors.forename: Patrizia
authors.initials: P
authors.lastname: Civolani
authors.forename: Manuela
authors.initials: M
authors.lastname: Porcu
authors.forename: Luigi
authors.initials: L
authors.lastname: Minerba
authors.forename: Maria Rosaria
authors.initials: MR
authors.lastname: Casini
mesh_terms: D000293:Adolescent; D058647:Adrenergic alpha-2 Receptor Agonists / Q000494:pharmacology; D000328:Adult; D000704:Analysis of Variance; D015992:Body Mass Index; D002648:Child; D003000:Clonidine / Q000494:pharmacology*; D005260:Female; D006130:Growth Disorders / Q000097:blood* / Q000175:diagnosis; D019382:Human Growth Hormone / Q000097:blood* / Q000172:deficiency / Q000378:metabolism; D006801:Humans; D007334:Insulin-Like Growth Factor I / Q000378:metabolism; D008297:Male; D012044:Regression Analysis; D012189:Retrospective Studies; D012636:Secretory Rate / Q000187:drug effects
chemical_list: D058647:Adrenergic alpha-2 Receptor Agonists; D019382:Human Growth Hormone; D007334:Insulin-Like Growth Factor I; D003000:Clonidine