A PRELIMINARY REPORT ON LEPTIN BIOAVAILABILITY IN ADOLESCENT IDIOPATHIC SCOLIOSIS

Introduction Despite extensive research, the cause of adolescent idiopathic scoliosis (AIS) is still largely unclear. Girls with AIS tend to be taller and leaner, and have a lower body-mass index (BMI) and lower bone mass, than do healthy girls. Recent MRI studies have shown the presence of relative anterior spinal overgrowth in girls with AIS. The lower bone mineral status and BMI could be related to dysfunctional central regulation pathway of growth, bodyweight, and bone metabolism. Following several interesting reports on the role of leptin in regulation of the above pathway in animals and human beings, our recent study has shown a low leptin concentration in girls with AIS girls compared with healthy adolescents. This finding leads to our new hypothesis that abnormal leptin bioavailability could be associated with the lower bodyweight, lower bone mineral density, and relatively disproportional endochondral skeletal growth in AIS. This study aimed to investigate the leptin bioavailability in girls with AIS. Methods 53 girls with AIS and 27 healthy girls (aged 11–16 years) were recruited in this preliminary study. Clinical and anthropometric data were obtained. Blood samples were obtained for ELISA of leptin and soluble leptin receptor (sOB-R). Independent Student9s t test and multivariate regression were used in group comparison. Results The AIS group had significantly lower BMI and longer arm span than did controls. Additionally, girls with AIS had significantly higher soluble leptin receptor concentrations (22·1 ng/mL [□}6·9] vs 17·8 ng/mL [4·4]; p vs 8·7 ng/mL [□}6·0]) and the leptin/sOB-R ratio (0·38 [□}0·28] vs 0·56 [□}0·47]) were similar to that of the controls. In girls with AIS, the leptin, sOB-R, and the leptin/sOB-R ratio correlated well with bodyweight and BMI. After adjustment for BMI, sOB-R in girls with AIS was significantly higher than in controls (r=0·37, p=0·042). Conclusions This preliminary report showed that the soluble leptin receptor could be abnormal in girls with AIS. Leptin and sOB-R are related to bodyweight. sOB-R is a major modulator of leptin concentration in circulation, the abnormality of which may lead to the retention of leptin in the circulation and thus abnormal regulatory effect. In this study, girls with AIS had lower BMI and longer arm span, which may reflect the possible change resulting from abnormal leptin bioavailability. Further longitudinal study with larger sample size would be useful to help to understand the long-term effect of the low leptin and high sOB-R in girls with AIS on their bodyweight and skeletal development. It is also noteworthy to study the mechanism of increased sOB-R in AIS.