The Relationship between BMI, Height and Leptin, Insulin, IGF-I and IGFBP-3 in Obese Children

Yang, Seung; Oh, Phil Soo; Shin, Jeh Hoon

Abstract

PURPOSE
The prevalence and severity of childhood obesity are increasing rapidly worldwide. Spontaneous and stimulated growth hormone (GH) secretion are impaired in obesity. However, despite the low GH levels, normal or increased insulin-like growth factor-I (IGF-I) levels have been observed in obese subjects. Growth velocity is commonly normal or increased in obese children. As for the possible mechanisms underlying these observations, overnutrition, chronic hyperinsulinemia and increased free IGF-I have been suggested. To explain the possible mechanisms by which obese children are taller than normal weight children, we have compared height, leptin, insulin, IGF-I and IGF binding protein-3 (IGFBP-3) with body mass index and studied the relationship among these parameters in obese and control group.
METHODS
Auxological and endocrine evaluation were performed in 33 obese children (18 boys and 15 girls) and 47 non-obese children (24 boys and 23 girls) at Hanyang University Hospital from Jan. 1999 to Dec. 2000. Obesity was defined as a body mass index (BMI) greater than the 95th percentile for age and sex. Fasing blood samples were taken for the measurement of serum leptin, insulin, IGF-I and IGFBP-3 by radioimmunoassay.
RESULTS
The serum concentrations of leptin, insulin, IGF-I and IGFBP-3 were significantly higher in obese children than those in non-obese children. The serum concentrations of leptin (r=0.751, P=0.000), insulin (r=0.746, P=0.000) and IGF-I (SDS) (r=0.747, P=0.000) showed positive correlation to BMI. And the serum concentrations of IGFBP-3 showed positive correlation to BMI with low correlation coefficient respectively (r=0.275, P=0.015). The serum concentration of insulin correlated to that of IGF-I (SDS) positively (r=0.585, P=0.000).
CONCLUSION
This study suggest that increased sensitivity of GHR modulated by chronic hyperinsulinemia and increased circulating IGF-I produced by accumulated adipose tissue may enhance the growth in obese children.