title: TSH and free triiodothyronine concentrations are associated with weight loss in a lifestyle intervention and weight regain afterwards in obese children.
abstract: OBJECTIVE
  The impact of thyroid hormones on weight loss in lifestyle interventions and on weight regain afterwards is unknown. Therefore, we studied the relationships between TSH, free triiodothyronine (fT₃), free thyroxine (fT₄), and weight status, as well as their changes during and after a lifestyle intervention in obese children.
  
  
  METHODS
  We evaluated the weight status as BMI-SDS in 477 obese children (mean age 10.6±2.7 years, 46% male, mean BMI 28.1±4.5  kg/m²) participating in a 1-year lifestyle intervention in a 2-year longitudinal study. Changes in BMI-SDS at 1 and 2 years were correlated with TSH, fT₃, and fT₄ concentrations at baseline and their changes during the intervention.
  
  
  RESULTS
  A decrease in BMI-SDS during the intervention period (-0.32±0.38; P<0.001) was significantly positively associated with baseline TSH and fT₃ in multiple linear regression analyses adjusted for age, sex, pubertal stage, and baseline BMI-SDS. An increase in BMI-SDS after the end of the intervention (+0.05±0.36; P=0.011) was significantly related to the decreases in TSH and fT₃ during the intervention in multiple linear regression analyses adjusted for change in BMI-SDS during the intervention. In contrast to children with weight maintenance, children with weight regain after the end of the intervention demonstrated a decrease in their TSH levels (-0.1±1.6 vs +0.2±1.6  mU/l; P=0.03) and fT₃ (-0.2±1.1 vs +0.3±1.6  pg/ml; P<0.001) during the intervention.
  
  
  CONCLUSIONS
  The decreases in TSH and fT₃ concentrations during the lifestyle intervention were associated with weight regain after the intervention. Future studies should confirm that the decreases in TSH and fT₃ levels associated with weight loss are related to the change in metabolism such as resting energy expenditure.
authors.affiliation: Department of Pediatric Endocrinology, Diabetes and Nutrition Medicine, Vestische Hospital for Children and Children Datteln, University of Witten/Herdecke, Dr F Steiner Street 5, D-45711 Datteln, Germany.
authors.forename: Barbara
authors.initials: B
authors.lastname: Wolters
authors.forename: Nina
authors.initials: N
authors.lastname: Lass
authors.forename: Thomas
authors.initials: T
authors.lastname: Reinehr
mesh_terms: D000293:Adolescent; D015992:Body Mass Index; D002648:Child; D002657:Child Development; D004038:Diet, Reducing; D015444:Exercise; D005260:Female; D005500:Follow-Up Studies; D005858:Germany; D006801:Humans; D008019:Life Style; D008137:Longitudinal Studies; D008297:Male; D009765:Obesity / Q000097:blood* / Q000178:diet therapy / Q000517:prevention & control / Q000628:therapy*; D012008:Recurrence; D013972:Thyrotropin / Q000097:blood*; D013974:Thyroxine / Q000097:blood; D014284:Triiodothyronine / Q000097:blood*; D015430:Weight Gain; D015431:Weight Loss
chemical_list: D014284:Triiodothyronine; D013972:Thyrotropin; D013974:Thyroxine