Thyroid function and morphology in overweight and obese children and adolescents in a Chinese population

Objective : To investigate the changes in thyroid function and morphology in overweight and obese school-aged children and adolescents in Chinese population. Methods: Altogether, 880 children and adolescents were enrolled in a cross-sectional survey in Anhui Province and we assessed thyroid function, thyroid ultrasound, metabolic indicators and high-sensitivity C-reactive protein (hs-CRP) levels in 781 subjects, which were divided into obesity (n=327), overweight (n=242), and normal-weight (n=212) groups. Overweight and obese subjects were further divided into four subgroups according to thyroid peroxidase antibody and ultrasound pattern to compare thyroid function and morphology with or without thyroid autoimmune evidence. Results: Thyroid-stimulating hormone (TSH) and free 3,5,3'-triiodothyronine (FT 3), as well as thyroid volume, were found to be positively associated with body mass index Z-score, waist/hip ratio, waist/height ratio and/or waist circumference (WC). Conversely, free thyroxine was negatively associated with WC. The detection rates of thyroid nodules among these groups were not significantly different (p=0.828). Among the four subgroups in 569 overweight or obese subjects, the changes in thyroid function and volume were more obvious in group D which showed no autoimmune evidence. The levels of hs-CRP were also higher in the overweight and obese groups with or without autoimmune evidence than in the normal-weight group (p<0.05). Conclusion: Thyroid function and morphology may be affected in obese and overweight children and adolescents with elevated TSH, FT 3 and thyroid volume. The detection rates of thyroid nodules may not be affected by obesity. Alterations in thyroid function and morphology cannot be completely explained by local autoimmune responses. Low-grade inflammation may be involved in the changes in thyroid function and morphology in obesity.