Thyroid Volume and Thyroid Function Parameters Are Independently Associated with Weight Status in Overweight Children.
BACKGROUND
A relation between thyroid-stimulating hormone (TSH), insulin resistance - both of which are related to obesity - and thyroid volume has been suggested. Therefore, we analyzed thyroid volume and structure in relation to thyroid function parameters, weight status, and insulin resistance.


METHODS
This is a cross-sectional study in which weight status (BMI-SDS), thyroid function parameters (TSH, free tri-iodothyronine [fT3], and free thyroxine [fT4]), insulin resistance index (HOMA-IR), and thyroid volume (ultrasound) were determined in 617 overweight children (aged 10.4 ± 2.2 years, 50% male, BMI-SDS 2.5 ± 0.6) and in 27 normal-weight children of a similar age and gender. Furthermore, changes in thyroid volume and structure, and thyroid function parameters were analyzed in 83 obese children (51% male, mean age 10.3 ± 2.2) at baseline and at the end of a 1-year lifestyle intervention.


RESULTS
Overweight children had a significant greater thyroid volume (4.2 ± 1.8 vs. 4.1 ± 0.5 mL) and higher TSH (3.1 ± 1.5 vs. 2.4 ± 1.1 mU/L) and fT3 (4.4 ± 0.7 vs. 4.1 ± 0.5 pg/mL) concentrations compared to normal-weight children. In multiple linear regression analyses adjusted to multiple confounders, thyroid volume was significantly related to BMI-SDS (b coefficient 0.44 ± 0.10, r2 = 0.41) but not to any thyroid function parameter or HOMA-IR. Changes in BMI-SDS were significantly associated with changes in thyroid volume (r = 0.22). The changes in thyroid volume were not correlated to changes of any thyroid function parameter or HOMA-IR.


CONCLUSIONS
Thyroid volume is positively correlated to weight status in childhood obesity and the change is reversible after weight loss independently of thyroid function parameters and insulin resistance. Further studies are needed to understand why thyroid volume is increased reversibly in overweight children.
['Lass|Nina|N|', 'Barth|Andre|A|', 'Reinehr|Thomas|T|']
D000293:Adolescent D001835:Body Weight D016022:Case-Control Studies D002648:Child D003430:Cross-Sectional Studies D005260:Female D006801:Humans D007333:Insulin Resistance D008297:Male D009929:Organ Size D063766:Pediatric Obesity D013961:Thyroid Gland D013972:Thyrotropin D013974:Thyroxine D014284:Triiodothyronine D014463:Ultrasonography D061217:Weight Reduction Programs
Thyroid volume Obesity Lifestyle intervention Weight loss Thyroid hormones