title: Lack of association between peripheral activity of thyroid hormones and elevated TSH levels in childhood obesity.
abstract: OBJECTIVE
  An elevated thyroid stimulating hormone (TSH) level is a frequent finding in obese children, but its association with peripheral hormone metabolism is not fully understood. We hypothesized that in obesity, the changes in thyroid hormone metabolism in peripheral tissues might lead to dysregulation in the thyroid axis. The purpose of this study was to investigate the association of TSH with thyroid hormones in a group of obese children as compared to normal-weight controls.
  
  
  METHODS
  Serum TSH, free thyroxine (fT4) and free triiodothyronine (fT3) levels were measured in 101 obese children and in 40 controls. Serum reverse T3 (rT3) levels were also measured in a subgroup of 51 obese children and in 15 controls.
  
  
  RESULTS
  Serum TSH level was significantly higher in obese children compared to controls (2.78 vs. 1.99 mIU/L, p<0.001), while no difference was found in fT4, fT3, rT3 levels and in fT3/rT3 ratio. In the obese group, fT3 level positively correlated with fT4 (r=0.217, p=0.033) and inversely with rT3 (r=-0.288, p=0.045). However, thyroid hormone levels and TSH levels were not correlated.
  
  
  CONCLUSIONS
  In obese children, normal fT4, fT3 and rT3 levels suggest an undisturbed peripheral hormone metabolism. These levels show no correlation with elevated TSH levels.
authors.affiliation: Comenius University Faculty of Medicine and Children's University Hospital, Department of Pediatrics, Bratislava, Slovakia. E-ma-il: ticha.lubica@gmail.com.
authors.forename: Denisa
authors.initials: D
authors.lastname: Lobotková
authors.forename: Daniela
authors.initials: D
authors.lastname: Staníková
authors.forename: Juraj
authors.initials: J
authors.lastname: Staník
authors.forename: Ol'ga
authors.initials: O
authors.lastname: Cervenová
authors.forename: Vladimír
authors.initials: V
authors.lastname: Bzdúch
authors.forename: L'ubica
authors.initials: L
authors.lastname: Tichá
mesh_terms: D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D008297:Male; D063766:Pediatric Obesity / Q000097:blood*; D013963:Thyroid Hormones / Q000097:blood*; D013972:Thyrotropin / Q000097:blood*; D013974:Thyroxine / Q000097:blood; D014284:Triiodothyronine / Q000097:blood; D014285:Triiodothyronine, Reverse / Q000097:blood
chemical_list: D013963:Thyroid Hormones; D014284:Triiodothyronine; D014285:Triiodothyronine, Reverse; D013972:Thyrotropin; D013974:Thyroxine