Circulating soluble leptin receptor, leptin, and insulin resistance before and after weight loss in obese children.
OBJECTIVE
To study the relationships between leptin, soluble leptin receptor (sOB-R), and insulin resistance in obese children before and after weight reduction.


METHODS
We determined fasting serum leptin, sOB-R, and insulin resistance index (Homeostasis model assessment (HOMA)) in 36 obese children at baseline and 1 y later and compared them to 72 lean children matched for age, gender, and pubertal stage. The changes of leptin (Deltaleptin) and sOB-R (DeltasOB-R) over the 1 y period were correlated to the changes of HOMA (DeltaHOMA), the changes of weight status, and the changes of percentage body fat (Delta%BF) based on skinfold measurements. Multiple linear regression analyses were conducted for the dependent variables Deltaleptin and DeltasOB-R, including DeltaBMI and DeltaHOMA as independent variables adjusted for age, gender, and pubertal stage. Changes of leptin and sOB-R levels were analyzed in 11 obese children after they had lost weight substantially (decrease SDS-BMI>0.5) and compared to 11 obese children without substantial weight loss matched for age, gender, and pubertal stage.


RESULTS
Obese children showed significantly (P<0.001) higher leptin and lower sOB-R levels. Deltaleptin correlated significantly to DeltaSDS-BMI (r=0.28, P<0.05), Delta%BF (r=0.44, P<0.05), and DeltaHOMA (r=0.42, P<0.01), while DeltasOB-R correlated significantly to DeltaSDS-BMI (r=-0.42, P<0.01) and Delta%BF (r=-0.47, P<0.01), but not to DeltaHOMA. In contrast to DeltasOB-R, Deltaleptin correlated significantly to DeltaHOMA (P=0.02) in multiple linear regression analysis. Substantial weight loss led to a significant increase in sOB-R (P=0.02) and to a decrease in HOMA (P=0.02). In children without substantial weight loss, there were no changes in sOB-R, while HOMA (P=0.04) and leptin (P=0.02) increased significantly.


CONCLUSIONS
The decrease of sOB-R and the increase of leptin levels in obese children normalized after weight loss. Therefore, these changes are consequences rather than the cause of overweight. In contrast to sOB-R, leptin levels are associated with insulin resistance.
Reinehr
T
T
Vestische Hospital for Children and Adolescents Datteln, University of Witten/Herdecke, Germany. T.Reinehr@kinderklinik-datteln.de
Kratzsch
J
J
Kiess
W
W
Andler
W
W
D000293:Adolescent; D000367:Age Factors; D002648:Child; D005260:Female; D006706:Homeostasis / Q000502:physiology; D006801:Humans; D007333:Insulin Resistance / Q000502:physiology*; D020738:Leptin / Q000097:blood*; D008297:Male; D009765:Obesity / Q000097:blood*; D011956:Receptors, Cell Surface / Q000097:blood*; D054411:Receptors, Leptin; D015431:Weight Loss / Q000502:physiology*
C515448:LEPR protein, human; D020738:Leptin; D011956:Receptors, Cell Surface; D054411:Receptors, Leptin