Ethnic differences in androgens, IGF-I and body fat in healthy prepubertal girls.
OBJECTIVE
To examine ethnic differences in adrenal androgen production, IGF-I, and IGFBP-1 and -3 in relation to bone age, insulin, and body composition in healthy prepubertal girls.


METHODS
Serum levels of DHEA-S, androstenedione, IGF-I, and IGFBP-1 and -3 were examined in relation to bone age, insulin, and body composition (determined by dual-energy X-ray absorptiometry) in 47 (19 Caucasian, 9 African-American, 19 Mexican-American) healthy prepubertal girls aged 7.5-9.0 years.


RESULTS
Age, weight, height, bone age, androstenedione, insulin, glucose:insulin ratios, and IGFBP-3 levels were not statistically different among groups. Mexican-American girls had higher % body fat than African-Americans or Caucasians (P < 0.001). DHEA-S levels in African-Americans were twofold higher than in Caucasians (P = 0.024), although their % body fat was not significantly different (16.1% and 19.4%, respectively; P = 0.138). DHEA-S levels in Mexican-American girls were intermediate. Bone age and weight were significant covariates for DHEA-S levels. Plasma IGF-I levels were also higher in African-American than in Caucasian or Mexican-American girls (P = 0.009). Covariance analysis showed that IGF-I levels were influenced mainly by ethnicity (P = 0.009) and were independent of bone age. Despite similar insulin levels among groups, IGFBP-1 levels were higher in Caucasians than in Mexican-Americans or African-Americans (P < 0.001).


CONCLUSIONS
In healthy prepubertal girls, DHEA-S concentrations are higher in African-Americans than in Caucasians or Mexican-Americans, even before any clinical evidence of adrenarche. Furthermore, IGF-I concentrations are higher in African-American girls than in Caucasian or Mexican-American girls which may contribute to the higher DHEA-S levels observed. Conversely, higher DHEA-S and IGF-I levels in African-American girls may be indicative of an influence not only of gonadal but also of adrenal androgens on the GH/IGF-I axis.
Girgis
R
R
Department of Pediatrics, Baylor College of Medicine and Texas Children's Hospital, Houston, USA. rgirgis@gpu.srv.ualberta.ca
Abrams
S A
SA
Castracane
V D
VD
Gunn
S K
SK
Ellis
K J
KJ
Copeland
K C
KC
D000273:Adipose Tissue / Q000033:anatomy & histology*; D000365:Age Determination by Skeleton; D000735:Androstenedione / Q000032:analysis*; D044383:Black People; D002648:Child; D019314:Dehydroepiandrosterone Sulfate / Q000097:blood*; D005260:Female; 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*; D017058:Mexican Americans; D011627:Puberty / Q000502:physiology*; D044465:White People; D001741:Black or African American
D018970:Insulin-Like Growth Factor Binding Protein 1; D018972:Insulin-Like Growth Factor Binding Protein 3; D000735:Androstenedione; D019314:Dehydroepiandrosterone Sulfate; D007334:Insulin-Like Growth Factor I