Triiodothyronine/Thyroxine Ratio and Metabolic Connections: Exploring Hyperthyrotropinemia in Childhood Obesity

Objective: Subclinical hypothyroidism (ScH) is characterized by elevated thyroid-stimulating hormone (TSH) levels while serum thyroxine (T4) concentrations remain within normal limits.Despite the well-documented association between obesity and ScH, the underlying mechanisms remain poorly understood.This study aims to investigate thyroid functions in both obese and non-obese children and adolescents, examining TSH, T4, and T3 levels alongside anthropometric measurements and to explore potential associations between thyroid hormone levels and metabolic parameters in obese children. Methods:In this retrospective study, medical records of children aged 5-18 years presenting for obesity evaluation were analyzed.Participants were categorized into two groups: Obese (body mass index [BMI] 95th percentile) and control (<95th percentile).The obese group was further stratified into those with high TSH (>4.5 IU/mL) and normal TSH (4.5 IU/mL).Anthropometric measurements, pubertal status, and biochemical parameters, including TSH, free triiodothyronine (fT3), fT4, and metabolic markers, were assessed.Results: A total of 98 children (66 obese, 32 controls) were included.Within the obese group, children with high TSH exhibited significantly lower fT4 levels (p=0.021)but did not differ in fT3 levels, fT3/fT4 ratio, BMI, waist circumference, or metabolic parameters, including glucose, insulin resistance, and lipid profile.No significant correlation was observed between TSH levels and insulin resistance. Conclusion:Our findings suggest that ScH in childhood obesity is associated with lower free thyroxine levels.However, metabolic alterations, including insulin resistance and dyslipidemia, were not found to be directly related to TSH levels.Future studies should aim to clarify the long-term implications of ScH in pediatric obesity and identify optimal management strategies for affected children.