title: Ghrelin and growth hormone serum levels during the clonidine test in children with short stature and variable growth hormone status.
abstract: OBJECTIVE
  The exact role of ghrelin in the control of growth hormone (GH) secretion has not been completely clarified as yet. The aim of the present study was 1) to investigate the effect of a substance promoting GH secretion (clonidine) on ghrelin levels in children with short stature with growth hormone deficiency (GHD) and normal growth hormone (NGH), and 2) to assess possible correlations between GH and ghrelin values during the clonidine test.
  
  
  METHODS
  Eighteen prepubertal children with short stature were included in the study. Using the results of two GH-provocative tests (glucagon and clonidine), the participants were divided into two groups: GHD and NGH. In both groups, ghrelin levels were determined during the clonidine stimulation test.
  
  
  RESULTS
  Different responses regarding ghrelin levels during the clonidine stimulation test were observed in the two study groups (GHD and NGH). A decrease in ghrelin levels was observed in the NGH children accompanied by a rise in the circulating GH levels, whereas the GHD children demonstrated a rise in both ghrelin and GH levels.
  
  
  CONCLUSIONS
  The data indicate an inverse relationship between circulating ghrelin and GH in NGH children, suggesting the presence of a negative feedback loop between ghrelin and GH. Analogous changes were not observed in GHD children.
authors.affiliation: Fourth Department of Pediatrics, Medical School, Aristotle University, Thessaloniki, Greece. chstylianou@gmail.com
authors.forename: Charilaos
authors.initials: C
authors.lastname: Stylianou
authors.forename: Assimina
authors.initials: A
authors.lastname: Galli-Tsinopoulou
authors.forename: Maria G
authors.initials: MG
authors.lastname: Grammatikopoulou
authors.forename: George
authors.initials: G
authors.lastname: Koliakos
authors.forename: George
authors.initials: G
authors.lastname: Varlamis
mesh_terms: D058647:Adrenergic alpha-2 Receptor Agonists; D001827:Body Height / Q000502:physiology; D002648:Child; D003000:Clonidine / Q000494:pharmacology; D003940:Diagnostic Techniques, Endocrine / Q000592:standards; D004393:Dwarfism, Pituitary / Q000097:blood* / Q000175:diagnosis*; D005260:Female; D054439:Ghrelin / Q000097:blood*; D006304:Health Status; D019382:Human Growth Hormone / Q000097:blood* / Q000172:deficiency / Q000378:metabolism; D006801:Humans; D008297:Male; D012016:Reference Values; D013997:Time Factors
chemical_list: D058647:Adrenergic alpha-2 Receptor Agonists; D054439:Ghrelin; D019382:Human Growth Hormone; D003000:Clonidine