Prevalence of thyroid dysfunction in obese children and adolescents before and after weight reduction and its relation to other metabolic parameters.

Aim: To establish the prevalence of elevated thyroid-stimulating hormone (TSH) levels in obese children and adolescents, and identify the relationship between changes in TSH levels and other metabolic and hormonal variables before and after weight reduction.

Methods: 207 obese participants aged 5-18 years were evaluated for anthropometric, biochemical, metabolic and hormonal variables before and after a weight reduction.

Results: At baseline, 46 participants (22.2%) had hyperthyrotropinemia (> or =4.0 mIU/l). Free T(4) levels were normal in all cases. Triglyceride levels were significantly higher in participants with hyperthyrotropinemia than in those with normal thyroid function (p = 0.011). Baseline TSH was significantly correlated with triglyceride levels (r = 0.261, p < 0.001), but not with age, anthropometric, or laboratory variables. Of the 142 participants who completed the intervention, 27 (19 %) had hyperthyrotropinemia. There was no significant relationship between changes in TSH level and changes in body mass index-standard deviation score. A significant correlation was found between the final TSH level and triglyceride level (r = 0.167, p = 0.045), and between the decrease in TSH level and the decrease in waist circumference (r = 0.291, p = 0.013).

Conclusions: In obese children, hyperthyrotropinemia with normal free T(4) levels appears to be frequent. The correlation of hyperthyrotropinemia with waist circumference and higher triglyceride levels raises the question of the necessity to treat the elevated TSH levels.