The effect of obesity-related allostatic changes on cardio-metabolic risk in euthyroid children

Purpose The hormonal thyroid changes related to obesity, even when in the euthyroid state, may contribute to the unfavorable cardio-metabolic profile of obese patients. In this retrospective study, we aim to investigate the biochemical thyroid changes and the association between serum TSH, FT4, FT3 and cardio-metabolic risk factors in euthyroid obese youths. Methods Four hundred ninety-one Caucasian euthyroid obese children and adolescents aged 9.93 +/- 2.90 years were recruited. Each patient underwent clinical and auxological examination and laboratory workup including an OGTT and the measurement of thyroid function and lipid profile. Homeostasis model assessment of insulin resistance (HOMA-IR), triglyceride to high-density lipoprotein cholesterol ratio, total cholesterol to HDL ratio, atherogenic index of plasma, insulinogenic index, area under the glucose and insulin curves were calculated. Results We found that TSH was positively correlated with BMI-SDS values and significantly associated with hypercholesterolemia and hyperinsulinemia; FT4 resulted negatively correlated with BMI-SDS; FT3 was positively correlated with BMI-SDS and the area under the curve of insulin and negatively correlated with HDL. FT3 and FT4 resulted significantly associated with severe obesity. In addition, children with high-normal TSH values showed higher triglyceride to high-density lipoprotein cholesterol ratio values than those with normal TSH levels. Conclusions Our data showed that thyroid hormones could influence obesity, lipid and glycemic parameters in euthyroid youths. These findings could carry implications regarding optimal TSH levels in obese children and confirm the importance of evaluating the thyroid function as possible adjunctive cardio-metabolic risk factor related to obesity.