title: Growth hormone secretory pattern in non-obese children and adolescents with Prader-Willi syndrome.
abstract: The aetiology of impaired growth hormone (GH) secretion in Prader-Willi syndrome (PWS) remains controversial due to the common occurrence of obesity. To further clarify whether suboptimal GH secretion in PWS is an artefact of excess weight, we evaluated both GH immunological activity and GH bioactivity after arginine administration in 23 non-obese PWS patients [seven females, aged 6.9 +/- 0.9 years, body mass index (BMI) SDS 0.63 +/- 0.26], in comparison with a control group of 32 healthy subjects, matched for age, gender and BMI (10 females, aged 7.9 +/- 0.3 years, BMI SDS 0.21 +/- 0.20). Serum GH concentration was measured with a time-resolved immunofluorometric assay (IFMA), while GH bioactivity was evaluated by the Nb2 cell bioassay. Serum IGF-I concentrations were measured by double-antibody RIA. GH mean peak after pharmacological stimulation was significantly lower in PWS individuals compared with controls when measured either by IFMA (6.05 +/- 1.23 microg/L vs. 23.7 +/- 1.06 microg/L, p < 0.0001) or by Nb2 (6.87 +/- 0.55 microg/L vs. 12.88 +/- 0.19 microg/L, p < 0.0001). Analysis of integrated GH secretion (AUC) confirmed that the PWS group differed significantly from the control subjects (387.9 +/- 76.1 microg/L/h vs. 1498.1 +/- 56.2 microg/L/h, p < 0.0001); the same result was obtained when the GH rise after arginine administration was expressed as nAUC (278.2 +/- 53.3 microg/L/h vs. 1443.6 +/- 52.5 microg/L/h, p < 0.0001). PWS patients had an IGF-I SDS significantly lower than those found in control subjects (p < 0.0001). Subnormal IGF-I values were present in 19 PWS individuals (82.6%) and two healthy controls (6.2%). These findings are in agreement with the hypothesis that a complex derangement of hypothalamus-pituitary axis occurs in PWS.
authors.affiliation: Department of Auxology, S. Giuseppe Hospital, Research Institute, Italian Auxological Institute Foundation, Verbania, Italy. g.grugni@auxologico.it
authors.forename: Graziano
authors.initials: G
authors.lastname: Grugni
authors.forename: Antonino
authors.initials: A
authors.lastname: Crinò
authors.forename: Sara
authors.initials: S
authors.lastname: Pagani
authors.forename: Cristina
authors.initials: C
authors.lastname: Meazza
authors.forename: Fabio
authors.initials: F
authors.lastname: Buzi
authors.forename: Teresa
authors.initials: T
authors.lastname: De Toni
authors.forename: Luigi
authors.initials: L
authors.lastname: Gargantini
authors.forename: Alba
authors.initials: A
authors.lastname: Pilotta
authors.forename: Giovanni B
authors.initials: GB
authors.lastname: Pozzan
authors.forename: Giorgio
authors.initials: G
authors.lastname: Radetti
authors.forename: Letizia
authors.initials: L
authors.lastname: Ragusa
authors.forename: Alessandro
authors.initials: A
authors.lastname: Salvatoni
authors.forename: Alessandro
authors.initials: A
authors.lastname: Sartorio
authors.forename: Mauro
authors.initials: M
authors.lastname: Bozzola
mesh_terms: D000293:Adolescent; D001120:Arginine / Q000494:pharmacology; D015992:Body Mass Index; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D002648:Child; D002675:Child, Preschool; D005260:Female; D015200:Fluoroimmunoassay; D019382:Human Growth Hormone / Q000097:blood / Q000378:metabolism*; D006801:Humans; D007334:Insulin-Like Growth Factor I / Q000032:analysis; D008223:Lymphoma / Q000378:metabolism; D008297:Male; D009765:Obesity / Q000209:etiology; D011218:Prader-Willi Syndrome / Q000097:blood / Q000378:metabolism* / Q000503:physiopathology; D011388:Prolactin / Q000037:antagonists & inhibitors; D015203:Reproducibility of Results; D012636:Secretory Rate / Q000187:drug effects
chemical_list: D019382:Human Growth Hormone; D007334:Insulin-Like Growth Factor I; D011388:Prolactin; D001120:Arginine