Alterations in markers of bone metabolism and adipokines following a 3-month lifestyle intervention induced weight loss in obese prepubertal children.

ABSTRACT

BACKGROUND: Adipokines may influence bone metabolism in children, but this phenomenon is not well understood. Therefore, we studied the relationships between bone markers and adipokines during weight loss in obese children. MATERIALS AND METHODS: We determined serum leptin, soluble leptin receptor (sOB-R), adiponectin, BALP (bone alkaline phosphatase), CTX-I (C-terminal telopeptide of type I collagen), body composition and bone mineral density (by dual-energy X-ray absorptiometry) in 100 obese prepubertal children before and after 3 months of lifestyle intervention (low-energy diet, physical activity). The control group consisted of 70 non-obese children. RESULTS: Obese children had higher BALP activity by about 20% (p<0.001) and similar value of CTX-I compared with non-obese children. After weight loss (-0.96 BMI-SDS mean change), the BALP value in obese patients decreased (p<0.001), whereas CTX-I concentration was unchanged. Changes in BALP were positively correlated with changes in BMI (Body Mass Index) (r=0.352, p<0.001), but not associated with adipokine levels. Trend analysis using SDS-BMI subgroups showed that greater reduction of body mass was associated with a greater decrease of BALP (p=0.035) and leptin values (p<0.001), as well as a greater increase of sOB-R (p<0.003). CONCLUSIONS: Obesity during the prepubertal period is associated with an alteration in the adipokines profile and greater whole-body bone mass as a result of increased bone formation rather than reduced bone resorption. Changes in bone metabolism during lifestyle intervention seem to be related to weight loss but not to changes in adipokines. Further studies should elucidate the influence of long-term therapy on bone mass in childhood.