title: Growth hormone status in morbidly obese subjects and correlation with body composition.
abstract: Morbidly obese subjects are characterized by multiple endocrine abnormalities and these are paralleled by unfavorable changes in body composition. In obese individuals, either 24-h spontaneous or stimulated GH secretion is impaired without an organic pituitary disease and the severity of the secretory defect is proportional to the degree of obesity. The GHRH+arginine (GHRH+ARG) test is likely to be the overall test of choice in clinical practice to differentiate GH deficiency (GHD) patients. Similarly to other provocative tests, GHRH+ARG is influenced by obesity per se. Therefore, a new cut-off limit of peak GH response of 4.2 microg/l in obese subjects has been recently assumed. The aim of the present study was to investigate the reciprocal influence between decreased GH secretion and body composition in a group of 110 morbidly obese subjects, using the new cut-off limit of peak GH response to GHRH+ARG test for these subjects. In our study, GHD was identified in 27.3% of the obese subjects, without gender difference. In GDH obese subjects body mass index (BMI), waist circumference, waist-to-hip ratio (WHR), fat mass (FM), and resistance (R) were higher while reactance (Xc), phase angle, body cell mass (BCM), IGF-I, or IGF-I z-scores were lower than in normal responders (p<0.001). In all obese subjects, GH peak levels showed a negative correlation with age, BMI, waist circumference and FM, and a positive correlation with IGF-I. In the stepwise multiple linear regression, waist circumference and FM were the major determinants of GH peak levels and IGF-I. In conclusion, using the new cut-off limit of peak GH response to GHRH+ARG test for obese subjects, about 1/3 morbidly obese subjects were GHD. GHD subjects showed a significantly different body composition compared with normal responders, and the secretory defect was correlated to different anthropometric variables with waist circumference and FM as the major determinants.
authors.affiliation: Division of Endocrinology, Department of Molecular and Clinical Endocrinology and Oncology, University Federico II, Naples, Italy. sisavast@unina.it
authors.forename: S
authors.initials: S
authors.lastname: Savastano
authors.forename: C
authors.initials: C
authors.lastname: Di Somma
authors.forename: A
authors.initials: A
authors.lastname: Belfiore
authors.forename: B
authors.initials: B
authors.lastname: Guida
authors.forename: F
authors.initials: F
authors.lastname: Orio
authors.forename: F
authors.initials: F
authors.lastname: Rota
authors.forename: M C
authors.initials: MC
authors.lastname: Savanelli
authors.forename: T
authors.initials: T
authors.lastname: Cascella
authors.forename: A
authors.initials: A
authors.lastname: Mentone
authors.forename: L
authors.initials: L
authors.lastname: Angrisani
authors.forename: G
authors.initials: G
authors.lastname: Lombardi
authors.forename: A
authors.initials: A
authors.lastname: Colao
mesh_terms: D000273:Adipose Tissue / Q000033:anatomy & histology; D000328:Adult; D000886:Anthropometry; D001120:Arginine; D001823:Body Composition / Q000502:physiology*; D015992:Body Mass Index; D017097:Electric Impedance; D005260:Female; D013007:Growth Hormone-Releasing Hormone; D019382:Human Growth Hormone / Q000097:blood* / Q000172:deficiency / Q000378:metabolism; D006801:Humans; D008297:Male; D009767:Obesity, Morbid / Q000503:physiopathology*; D012044:Regression Analysis; D049629:Waist-Hip Ratio
chemical_list: D019382:Human Growth Hormone; D013007:Growth Hormone-Releasing Hormone; D001120:Arginine