Endocrine Abstracts

Obesity and thyroid function in children – cross-sectional study.

Background: Obesity in children has been increasing dramatically, with a significant increase in cardiovascular and metabolic diseases risk. The role of thyroid dysfunction has been extensively analyzed in obese adults, but to a limited extent in children.

Aims: To estimate the prevalence of hyperthyrotropinemia in obese children and to analyze the influence of BMI–SDS and TSH in other metabolic variables.

Methods: Retrospective study with data from the first evaluation of obese children in our clinic. Demographic, anthropometric and metabolic variables were studied.

Descriptive analysis consisted of frequencies distribution for qualitative variables and mean±S.D. for continuous variables. For the association between BMI–SDS, thyroid function and other metabolic variables multiple linear regression models were used. A P value ≤0.05 was considered for statistical significance.

Results: We obtained data from 348 children with mean age of 11.7±3.1 years and mean BMI–SDS of 2.9±0.7. The prevalence of hyperthyrotropinemia was 8.9% and of homeostasis model assessment-insulin resistance (HOMA-IR) elevation was 69.3%. Children with hyperthyrotropinemia revealed fT₃ and HOMA-IR significantly higher than those with normal serum values. BMI–SDS was positively correlated with TSH and fT₄ but not with fT₃, when controlled for sex, age and pubertal stage. BMI–SDS and TSH were positively and independently correlated with HOMA-IR, but not with the lipids.

Conclusions: The prevalence of hyperthyrotropinemia was similar to that reported in other studies and appeared to be influenced by metabolic factors other than fT₃ or TRH. Children with hyperthyrotropinemia had significantly higher fT₃ and HOMA-IR. BMI–SDS was positively correlated with TSH, fT₄ and HOMA-IR. TSH and BMI–SDS were positively and independently correlated with HOMA-IR, which suggests that hyperthyrotropinemia might exacerbate insulin resistance in obese children.