Insulin-like growth factors and their binding proteins before and after weight loss and their associations with hormonal and metabolic parameters in obese adolescent girls.

OBJECTIVE

To investigate serum concentrations of insulin-like growth factors (IGF) and IGF-binding proteins (IGFBP) in obese adolescent girls before and after weight reduction and to examine their associations with hormonal and metabolic parameters.

PATIENTS AND METHODS

73 girls (age: 15.0 +/- 1.1 y, BMI: 31.1 +/- 3.8 kg/m2) participated in this 6 w intervention study.

RESULTS

(1) Compared to 100 normal-weight girls of same age the obese subjects had increased levels of IGF-I, IGFBP-1, IGFBP-2, and IGFBP-3 and normal levels of IGF-II. (2) After weight loss (8.1 +/- 2.0 kg) IGF-II and IGFBP-2 increased and IGF-I, IGFBP-1, IGFBP-3 and the ratio IGF-I/IGFBP-3 decreased significantly. (3) Correlation analysis revealed that fasting insulin levels of the patients were positively correlated with IGF-I but inversely with IGFBP-1 and IGFBP-2. IGFBP-2 was associated with several metabolic parameters: it showed an inverse correlation with uric acid and triglyceride levels. The ratio IGFBP-2 to IGFBP-1 was inversely correlated with total cholesterol and LDL-cholesterol. In addition, IGFBP-2 was inversely correlated with the waist-to-hip ratio of the girls.

CONCLUSIONS

These studies of a homogeneous group of patients give further insight into possible physiological regulations and roles of IGFs and IGFBPs. The main conclusion is that obesity has to be considered for interpretation of serum concentrations of IGF-I, IGFBP-1, IGFBP-2, and IGFBP-3. Furthermore, out results suggest that (i) the decrease in IGF-I/IGFBP-3 after weight loss could be partly responsible for the impaired growth velocity seen in obese children during hypocaloric feeding and (ii) low IGFBP-2 and high IGFBP-1 levels are associated with an unfavorable atherogenic risk factor profile.