Serum IGF-I levels are similar in Samoan, Maori and European populations despite differences in body composition.

OBJECTIVE: To determine if serum IGF-I concentrations are similar in healthy adult subjects from the Samoan, Maori and European populations in New Zealand. DESIGN: Serum IGF-I concentration was measured in 75 healthy adults, aged 18-50 years, of Samoan (n=23), Maori (n=22) and European (n=30) descent. Body composition was assessed using standard anthropomorphic measures. In addition all subjects had body composition assessed by Dual energy X-ray absorptiometry (DXA). RESULTS: Weight, body mass index (BMI), and fat mass were significantly greater in Maori and Samoan subjects than European subjects (ANOVA p=0.006, p=0.0003, p=0.03, respectively). However, serum IGF-I concentration was similar between the groups (European 186.8 SEM 14.9 microg/l, Maori 204.8 SEM 17.1 microg/l, Samoan 180.0 SEM 17.5 microg/l, p=0.58). IGF-I levels were similar between ethnic groups after adjustment (ANCOVA) for age, sex or BMI (p=0.5) or age, sex and fat mass (p=0.44). In multivariate analysis the only independent predictor of IGF-I was age (p<0.001) and explained 22% of the variance in IGF-I level. CONCLUSIONS: Serum IGF-I concentrations were similar in Maori, Samoan and European population groups in New Zealand, despite significant differences in anthropomorphic variables and body composition.