Negative Association between Obesity Index and Thyroid Hormones in Euthyroid Children

ABSTRACT

BACKGROUND: The number of obese people is increasing worldwide; in particular, childhood obesity is becoming a major problem. Obesity elevates the risk of various endocrine-metabolic diseases, and it was recently reported that there was a correlation between obesity and thyroid hormone level. The present study aimed to investigate the correlation between the obesity index and thyroid hormone level in healthy children with normal thyroid function. METHODS: The study subjects included children 7-12 years of age with normal thyroid function who participated in follow-up observations from 2011 to 2014 as participants in the Ewha Infant Growth Cohort (2001-2006). Subjects with a body mass index (BMI) > or =85th percentile were classified in the overweight group for the analysis (37 subjects, 14.5%). RESULTS: No significant differences in thyroid-stimulating hormone (TSH) or free thyroxine (FT4) levels were observed between the overweight and normal groups containing a total of 256 children (122 boys, 134 girls). Waist circumference, BMI z score, and WHtR were negatively correlated with TSH levels after adjusting for age, sex, birth weight and puberty status (P=0.03, P=0.04, P=0.05). However other obesity index did not show any relationship with TSH or FT4 levels. CONCLUSION: In children with normal thyroid function, waist circumference and BMI z score showed a negative correlation with TSH levels.