Ethnicity affects IGFBP-3 and IGF-II in normal healthy young adult subjects.
OBJECTIVE
While the effects of age on the growth hormone/insulin-like growth factor (IGF) axis are well documented, the influence of ethnic background is unknown. The differences in IGF and IGF binding proteins (IGFBPs) were investigated in two ethnic groups.


METHODS
A cross-sectional study of an age-selected cohort of healthy, normoglycaemic, non-obese Caucasian (C) and Asian (A) subjects.


METHODS
Fifty-three (27 C, 26 A) subjects with a mean age (+/- SD) of 20.6 +/- 0.8 years were studied.


METHODS
Fasting measurements of glucose, insulin, IGF-I, IGF-II, IGFBP-1 and IGFBP-3. Western ligand blotting and immunoblotting with IGFBP-2 and IGFBP-3 of serum samples.


RESULTS
There were no significant differences in IGF-I levels between Caucasian and Asian subjects (C 218 +/- 55 vs A 229 +/- 40 micrograms/l; P = 0.44). IGF-II (C 707 +/- 110 vs A 583 +/- 75 micrograms/l; P < 0.0001) and IGFBP-3 (C 5.9 +/- 1.2 vs A 5.12 +/- 1.17 mg/l; P = 0.01) levels were significantly higher in Caucasian subjects. Immunoblotting of ligand blots revealed no protease activity on either IGFBP-3 or IGFBP-2 to account for these ethnic differences.


CONCLUSIONS
Ethnic differences in IGFBP-3 and associated IGF-II levels may affect the inter-relationships of IGFs and their binding proteins and need to be considered when interpreting IGF data on growth and metabolism.
Hopkins
K D
KD
Division of Medicine, St Thomas' Hospital, London, UK.
Lehmann
E D
ED
Jones
R L
RL
Holly
J M
JM
Cwyfan-Hughes
S C
SC
Turay
R C
RC
Teale
J D
JD
Gosling
R G
RG
D000328:Adult; D044466:Asian People; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D015151:Immunoblotting; D018971:Insulin-Like Growth Factor Binding Protein 2 / Q000097:blood; D018972:Insulin-Like Growth Factor Binding Protein 3 / Q000097:blood*; D007334:Insulin-Like Growth Factor I / Q000032:analysis; D007335:Insulin-Like Growth Factor II / Q000032:analysis*; D008297:Male; D044465:White People
D018971:Insulin-Like Growth Factor Binding Protein 2; D018972:Insulin-Like Growth Factor Binding Protein 3; D007334:Insulin-Like Growth Factor I; D007335:Insulin-Like Growth Factor II