Thyroid function tests in obese prepubertal children: correlations with insulin sensitivity and body fat distribution

Area of Science:

• Pediatric Endocrinology
• Metabolic Disorders
• Thyroid Function

Background:

• Obese children often exhibit elevated thyroid-stimulating hormone (TSH) with normal or slightly increased free triiodothyronine (fT3) and free thyroxine (fT4).
• Understanding the interplay between adiposity, insulin sensitivity, and thyroid hormones in this population is crucial.

Purpose of the Study:

• To investigate the associations between body fat, insulin sensitivity, and thyroid hormone levels (TSH, fT3, fT4) in overweight and obese children.

Main Methods:

• Studied 240 overweight/obese prepubertal children.
• Assessed fasting thyroid hormones, glucose, insulin, C-peptide, lipids, leptin, adiponectin.
• Measured body fat using dual-energy X-ray absorptiometry and calculated central obesity index.
• Estimated insulin sensitivity and resistance using QUICKI, ISI, and hepatic insulin resistance index.

Main Results:

• Insulin sensitivity (QUICKI) was a significant negative predictor of TSH.
• Central obesity index was the strongest positive predictor of fT3, linked with age or hepatic insulin resistance.
• Hepatic insulin resistance index was the sole positive determinant of fT4.

Conclusions:

• Reduced insulin sensitivity is associated with increased TSH and fT4 levels in obese children.
• Central fat accumulation is independently associated with higher fT3 levels.
• Further research is needed to elucidate the mechanisms connecting thyroid function, insulin sensitivity, and body composition in pediatric obesity.