title: Tracking of leptin, soluble leptin receptor, and the free leptin index during weight loss and regain in children.
abstract: OBJECTIVE
  To investigate changes in leptin and soluble leptin receptor (SLR) concentrations, and in the free leptin index (FLI) during weight loss and subsequent weight regain; and to ascertain whether these indices remain stable in the rank of the distribution in repeated measures (tracking) during perturbations of weight in obese children.
  
  
  METHODS
  In a longitudinal study, 115 obese children were examined during a 12- week weight loss programme and 28 months of follow-up. Height, weight, body composition, Tanner stages, testicular size, time of menarche, and concentrations of leptin and SLR were measured at baseline, on days 14, 33, and 82, and from months 10, 16, and 28.
  
  
  RESULTS
  During weight loss, leptin decreased and the SLR increased. During weight regain, leptin increased and the SLR decreased. The partial correlation coefficients expressing the relationship between leptin and SLR were significant in girls during both weight loss and weight regain, whereas in boys they were much weaker and not significant. Leptin, SLR and FLI exhibited individual-specific levels (tracking) during weight loss and regain in boys and girls. The observed tracking seemed stronger during weight loss than during weight regain. The observed tracking was independent of both baseline body mass index (BMI) standard deviation score (SDS) and pubertal development at baseline and of subsequent changes in BMI SDS and puberty stages.
  
  
  CONCLUSIONS
  Leptin and the SLR exhibit tracking during weight loss and regain, which indicates individual stability in the leptin system despite challenges of weight.
authors.affiliation: The Children's Obesity Clinic, Department of Paediatrics, Holbæk University Hospital, Holbæk, Denmark. jhom@regionsjaelland.dk
authors.forename: Jens-Christian
authors.initials: JC
authors.lastname: Holm
authors.forename: Michael
authors.initials: M
authors.lastname: Gamborg
authors.forename: Leigh C
authors.initials: LC
authors.lastname: Ward
authors.forename: Steen
authors.initials: S
authors.lastname: Gammeltoft
authors.forename: Karsten
authors.initials: K
authors.lastname: Kaas-Ibsen
authors.forename: Berit L
authors.initials: BL
authors.lastname: Heitmann
authors.forename: Thorkild I A
authors.initials: TI
authors.lastname: Sørensen
mesh_terms: D015992:Body Mass Index; D002648:Child; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D020738:Leptin / Q000097:blood*; D008137:Longitudinal Studies; D008297:Male; D009765:Obesity / Q000097:blood*; D011627:Puberty / Q000097:blood; D054411:Receptors, Leptin / Q000097:blood*; D012737:Sex Factors; D015430:Weight Gain / Q000502:physiology*; D015431:Weight Loss / Q000502:physiology*; D061217:Weight Reduction Programs
chemical_list: D020738:Leptin; D054411:Receptors, Leptin