title: Circulating ghrelin levels in basal conditions and during glucose tolerance test in acromegalic patients.
abstract: BACKGROUND
  Ghrelin exerts a wide range of metabolic functions. In contrast to the body of information accumulated on the role of ghrelin on energy balance, the possible relevance of the peptide on GH secretion in physiological and pathological conditions has so far been poorly investigated.
  
  
  OBJECTIVE
  The aim of the present study was to evaluate circulating ghrelin levels in acromegalic patients in basal conditions and in response to oral glucose tolerance test (OGTT).
  
  
  METHODS
  Serum ghrelin, insulin and leptin levels were measured in 31 healthy normal weight subjects as controls, 25 patients with simple obesity and 17 non-diabetic acromegalic patients. Ghrelin and insulin response to OGTT was evaluated in six controls, four obese and six acromegalic patients.
  
  
  RESULTS
  The acromegalic patients showed ghrelin levels lower than those observed in normal weight subjects (201+/-20 vs 329+/-32 pmol/l, P<0.05) and similar to those found in obese subjects (165+/-14 pmol/l, P=not significant). Both obese and acromegalic patients had insulin levels significantly higher than controls, while high levels of leptin were detected only in obese subjects. Serum ghrelin levels showed a significant negative correlation with insulin, leptin and body mass index (P<0.05) in normal and obese subjects. No correlation was observed in acromegalic patients, although those with severe insulin resistance showed the lowest ghrelin values (161+/-20 pmol/l). In controls and obese subjects, ghrelin levels showed a significant decrease (25-40%) during OGTT, while no effect was detectable in acromegalic patients.
  
  
  CONCLUSIONS
  This study reports that patients with active acromegaly show low levels of circulating ghrelin that are not further reduced by OGTT, this pattern of secretion probably depending on both GH-induced insulin resistance and the putative GH/IGF-I negative feedback control on ghrelin secretion.
authors.affiliation: Institute of Endocrine Sciences, University of Milan, Ospedale Maggiore IRCCS, Milan, Italy.
authors.forename: Vincenzo
authors.initials: V
authors.lastname: Cappiello
authors.forename: Cristina
authors.initials: C
authors.lastname: Ronchi
authors.forename: Paola S
authors.initials: PS
authors.lastname: Morpurgo
authors.forename: Paolo
authors.initials: P
authors.lastname: Epaminonda
authors.forename: Maura
authors.initials: M
authors.lastname: Arosio
authors.forename: Paolo
authors.initials: P
authors.lastname: Beck-Peccoz
authors.forename: Anna
authors.initials: A
authors.lastname: Spada
mesh_terms: D000172:Acromegaly / Q000097:blood*; D000328:Adult; D000368:Aged; D015992:Body Mass Index; D005260:Female; D054439:Ghrelin; D005951:Glucose Tolerance Test; D019382:Human Growth Hormone / Q000097:blood / Q000378:metabolism; D006801:Humans; D007328:Insulin / Q000097:blood; D007333:Insulin Resistance; D020738:Leptin / Q000097:blood; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000097:blood; D036361:Peptide Hormones; D010455:Peptides / Q000097:blood*
chemical_list: D054439:Ghrelin; D007328:Insulin; D020738:Leptin; D036361:Peptide Hormones; D010455:Peptides; D019382:Human Growth Hormone