ESPE Abstracts

Objectives: Increased central and peripheral sensitivity to thyroid hormones seems to be associated with an increased risk of developing prediabetes in adulthood. The objective of this study was to evaluate the relationship between the severity of obesity, the presence of glyco-metabolic alterations, and tissue sensitivity to thyroid hormones in prepubertal euthyroid children with simple obesity.

Methods: Eighty prepubertal children with simple obesity (Group 1; mean age 7.60 ± 1.51 years) and 28 healthy normal-weight controls matched for sex and age (Group 2), underwent clinical (height, weight, BMI, waist circumference) and biochemical (TSH, FT4, FT3, reverse T3 (rT3), leptin) evaluation; in patients with obesity were also evaluated fasting and OGTT glycemia and insulin, HbA1c, HOMA-IR, HOMA-β, insulinogenic index, Matsuda index, lipid profile. Insulin resistance (IR) was diagnosed in the presence of HOMA-IR values >2.5. In addition, indexes expressing peripheral sensitivity (FT3/FT4 ratio) and central sensitivity (TSH index, TSHI; TSH T4 resistance index, TT4RI; Thyroid Feedback Quantile-based Index, TFQI; Parametric Thyroid Feedback Quantile-based Index, PTFQI) to thyroid hormones were calculated.

Results: Patients in group 1 had significantly higher values of BMI (P=0.000) and leptin (P=0.000) than in group 2, but there were no significant differences for TSH, FT4, FT3, FT3/FT4. Patients had no alterations in fasting blood glucose or impaired glucose tolerance at OGTT. The FT3/FT4 ratio in group 1 correlated negatively with rT3 (r=-0.341; P=0.003), HOMA-β (r=-0.29; P=0.01) and was significantly associated with BMI (B=0.01; P=0.03), presence of IR (B= 0.11; P=0.03) and fasting blood glucose (B=0.004; P=0.04). In group 1, rT3 correlated negatively with the presence of IR (r = -0.23; P=0.042) and was significantly associated with BMI (B=-0.010; P=0.01) and HOMA-IR (B = -0.19; P=0.042). TT4RI, TSHI, PTFQI correlated negatively with FT3/FT4 ratio (P=0.000; P=0.005; P=0.042, respectively) and were negatively affected by BMI (B= -13.6, P=0.04; B= -0.29, P=0.035; B= -0.02, P=0.038, respectively) in group 1.

Conclusions: Central and peripheral sensitivity to thyroid hormones is significantly affected by the severity of obesity and the presence of IR. Altered tissue sensitivity to thyroid hormones in the obese prepubertal child could be implicated in the pathogenesis of changes in glucose metabolism and increased risk of prediabetes onset.