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. DESIGN A cross-secti onal study of an age-selected cohort of healthy, normoglycaemic, non-o bese Caucasian (C) and Asian (A) subjects. PATIENTS Fifty-three (27 C, 26 A) subjects with a mean age (+/- SD) of 20.6 +/- 0.8 years were st udied. MEASUREMENTS Fasting measurements of glucose, insulin, IGF-I, I GF-II, IGFBP-1 and IGFBP-3, Western ligand blotting and immunoblotting with IGFBP-2 and IGFBP-3 of serum samples. RESULTS There were no sign ificant differences in IGF-I levels between Caucasian and Asian subjec ts (C 218 +/- 55 vs A 229 +/- 40 mu g/l; P = 0.44), IGF-II (C 707 +/- 110 vs A 583 +/- 75 mu g/l; P < 0.001) and IGFBP-3 (C 5.9 +/- 1.2 vs A 5.12 +/- 1.17 mg/l; P = 0.01) levels were significantly higher in Cau casian subjects, Immunoblotting of ligand blots revealed no protease a ctivity on either IGFBP-3 or IGFBP-2 to account for these ethnic diffe rences, CONCLUSlONS Ethnic differences in IGFBP-3 and associated IGF-I I levels may affect the inter-relationships of IGFs and their binding proteins and need to be considered when interpreting IGF data on growt h and metabolism.