Leptin levels and IgF-binding proteins in malnourished children: effect of weight gain.

OBJECTIVES: Although it is well known that leptin reflects body fat content in adults, the regulation of leptin levels during childhood malnutrition is poorly understood. Insulin-like growth factor I (IGF-I) and the IGF-binding proteins (IGFBPs) may play important roles in the regulation of body composition. We investigated the relation between leptin, IGF-I, and IGFBPs in children with protein-energy malnutrition (PEM; before and after recovering 10% of their initial body weights) in comparison with well-nourished children. METHODS: Fifteen PEM and 16 healthy children were studied on admission and after 10% weight gains in the malnourished group. Leptin was measured with radioimmunoassay, IGF-I and IGFBPs were measured with immunoradiometric assay. RESULTS: Patients with PEM had a significantly lower body mass index and percentage of body fat than did the control children. Before weight gain, leptin, IGF-I, and IGFBP-3 were significantly lower and IGFBP-1 was elevated in the malnourished group compared with the control group. Among PEM patients, after 10% weight gains, the levels of leptin, IGF-I, and IGFBP-3 were significantly higher and IGFBP-1 significantly lower compared with the control group. Leptin correlated significantly with IGF-I in the normal children (r(s) = 0.86, P < 0.005). On admission, no correlation was observed between leptin and IGF-I (r(s) = 0.08, P < 0.16) and between leptin and IGFBP-3 (r(s) = 0.02, P < 0.27) in the malnourished group, but those levels improved after 10% recovery of their body weights (r(s) = 0.47, P < 0.002 and r(s) = 0.42, P < 0.005, respectively). In the PEM group, IGF-I correlated significantly with IGFBP-3 when the children gained weight (before: r(s) = 0.006, P < 0.31; after: r(s) = 0.32, P < 0.01). Our study showed results similar to those of anorexia nervosa studies, but the normalization of study variables was obtained in considerable less time for the same weight gain. CONCLUSIONS: The main finding of this study was that, after refeeding with only a 10% weight gain, the PEM children normalized their leptin, IGF-I, and IGFBP-3 levels. These results provide evidence that leptin can function as link between this hormonal response and improved nutrition status.