The association of thyroid-stimulating hormone (TSH) and free thyroxine (fT4) concentration levels with carbohydrate and lipid metabolism in obese and overweight teenagers

Introduction: Obesity has increased rapidly among children and adolescents during the last 30 years. Paediatric patients with a BMI above the 85th centile are more often diagnosed with increased TSH levels than are children with proper body weight. Material and methods: The data of 961 overweight and obese children, aged 13 years, recruited in four cities in Poland as part of PoZdro!, a two-year prophylactic program, were analysed to observe the relationship between serum TSH and fT4 concentration and carbohydrate and lipid metabolism parameters, as well as anthropometric parameters. Results: TSH concentration in the study group was positively correlated, whereas fT4 concentration was negatively correlated with WHR and WHtR values, fasting serum glucose concentrations and one-hour glucose concentration, fasting serum insulin concentrations, one-hour and two-hour insulin concentration, ALT serum activity, as well as total cholesterol, LDL cholesterol, and triglyceride serum concentrations. An increased risk of metabolic syndrome was diagnosed previously in patients with TSH concentrations > 2.5 mUI/L. Conclusions: TSH concentration in the upper half of the current reference range (> 2.50 mIU/L) is associated with an increased risk of lipid and carbohydrate metabolism disorders and therefore increased chances of developing metabolic syndrome. It seems advisable to regularly monitor thyroid function in overweight and obese paediatric patients.