Growth hormone secretion in response to glucagon stimulation test in healthy middle-aged men.
OBJECTIVE
To investigate the growth hormone (GH) response to glucagon stimulation test (GST) in a population of healthy men over 50 years old in comparison to insulin tolerance test (ITT), analysis of the spontaneous 24-hour GH profile and insulin-like growth factor 1 (IGF-I).


METHODS
27 healthy men aged between 51 and 65 years were tested.


RESULTS
Using non-parametric correlation analysis, a positive correlation between GH peak after GST and mean IGF-I (r = 0.528; p = 0.005) was found, as well with GH peak in 24-hour profile (r = 0.494; p = 0.009). No correlation was found comparing GH peak after ITT with the same parameters. Ten subjects presented GH peak of less than 3.0 microg/L after GST, none confirmed in ITT.


CONCLUSIONS
GH peak response to GST was lower than ITT, but it showed a positive correlation with mean IGF-I and also with GH peak in 24-hour profile. However, GST should not be used to differentiate organic growth hormone deficiency (GDH) from the expected decline on GH secretion due to aging.
Micmacher
Eduardo
E
Departamento de Endocrinologia, Hospital Universitário Clementino Fraga Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil. dudamicmacher@ig.com.br
Assumpção
Roberto P
RP
Redorat
Renato G
RG
Spina
Luciana D
LD
Cruz
Ivan C
IC
Silva
Carla A
CA
Vaisman
Mário
M
Conceição
Flávia Lúcia
FL
D000368:Aged; D005934:Glucagon; D019382:Human Growth Hormone / Q000378:metabolism*; D006801:Humans; D007328:Insulin; D007334:Insulin-Like Growth Factor I / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D018709:Statistics, Nonparametric
D007328:Insulin; D019382:Human Growth Hormone; D007334:Insulin-Like Growth Factor I; D005934:Glucagon