Ghrelin concentrations in healthy children and adolescents.
OBJECTIVE
In addition to its regulation by GH releasing hormone (GHRH) and somatostatin, release of GH from the pituitary is modulated by a third factor, ghrelin, which is expressed in high concentration in the stomach and is present in the circulation. Ghrelin has also been shown to cause weight gain by increasing food intake and decreasing fat utilization. Ghrelin is a potential candidate hormone to influence nutrient intake and growth. Its role through normal childhood and adolescence has not been fully defined.


METHODS
Cross-sectional study in 121 healthy children (65 male, 56 female) aged 5-18 years, in whom height, weight, body mass index (BMI), pubertal status and measurements of IGF-I, IGFBP-3, IGFBP-1 and leptin were available.


METHODS
Serum ghrelin concentrations have been measured in radioimmunoassay (RIA; Phoenix, AZ, USA) that detects active and inactive human ghrelin. Relationships between ghrelin and anthropometric data and growth factors were assessed by correlation and regression analyses.


RESULTS
Ghrelin was detected in all samples, with a median concentration of 162 pg/ml, range 60-493 pg/ml. Prepubertal children had higher ghrelin concentrations than those in puberty [218 pg/ml (n = 42) and 157 pg/ml (n = 79), P < 0.001], with significant negative correlations between ghrelin and age (rs = -0.39, P < 0.001) and pubertal stage (rs = -0.42, P < 0.001). The decrease in ghrelin with advancing pubertal stage/age was more marked in boys than girls. In the whole group, ghrelin was negatively correlated to BMI SD (rs = -0.24, P = 0.006) and to weight SD (rs = -0.24, P = 0.008) but not height sds. Ghrelin was also negatively correlated to IGF-I (rs = -0.48, P < 0.001), IGFBP-3 (rs = -0.32, P < 0.001) and leptin (rs = -0.22, P = 0.02) but not IGF-II. It was positively related to IGFBP-1 (rs = +0.46, P < 0.001). In stepwise multiple regression, 30% of the variability in ghrelin through childhood could be accounted for by log IGF-I (24%) and log IGFBP-1 (6%).


CONCLUSIONS
The fall in ghrelin over childhood and with puberty does not suggest that it is a direct growth-promoting hormone. However in view of the negative relationship with IGF-I and the positive relationship with IGFBP-1, this fall in ghrelin could facilitate growth acceleration over puberty.
Whatmore
A J
AJ
Endocrine Science Research Group, University of Manchester, UK.
Hall
C M
CM
Jones
J
J
Westwood
M
M
Clayton
P E
PE
D000293:Adolescent; D000328:Adult; D000367:Age Factors; D015992:Body Mass Index; D001835:Body Weight; D002648:Child; D002675:Child, Preschool; D003430:Cross-Sectional Studies; D005260:Female; D054439:Ghrelin; D006801:Humans; D018970:Insulin-Like Growth Factor Binding Protein 1 / Q000097:blood; D018972:Insulin-Like Growth Factor Binding Protein 3 / Q000097:blood; D007334:Insulin-Like Growth Factor I / Q000032:analysis; D020738:Leptin / Q000097:blood; D016014:Linear Models; D008297:Male; D036361:Peptide Hormones / Q000097:blood*; D011627:Puberty / Q000097:blood; D012737:Sex Factors; D018709:Statistics, Nonparametric
D054439:Ghrelin; D018970:Insulin-Like Growth Factor Binding Protein 1; D018972:Insulin-Like Growth Factor Binding Protein 3; D020738:Leptin; D036361:Peptide Hormones; D007334:Insulin-Like Growth Factor I