Altered Thyroid Function and Structure in Children and Adolescents Who Are Overweight and Obese: Reversal After Weight Loss.

Abstract

Obesity is associated with hypothyroidism and goiter. The aim of the study was to verify whether thyroid structure and function would improve after weight loss. We evaluated 96 children who were overweight/obese who showed an altered parenchymal pattern at thyroid ultrasound without circulating antithyroid antibodies. At phase 1, body mass index (BMI), SD score (SDS), body composition, free T4 (fT4), TSH, high-sensitivity C reactive protein (CRPhs), white blood cells, metabolic profile, and a thyroid ultrasound were assessed. Thyroid volume was expressed as SDS on the basis of the references values for age. Alterations in echogenicity and homogeneity were graded from 0 to 5 (thyroid score). The same parameters were re-examined after a weight loss program (phase 2). After a mean period of treatment of 0.8 ± 0.3 years, there was a significant decrease of BMI SDS, percentage fat mass, CRPhs, TSH, and thyroid volume SDS (all P < 0.0001), whereas fT4 remained unchanged. The thyroid score significantly improved (z = -9088; P < 0.0001) [i.e., it decreased in 82 individuals, was tied in 12, and worsened only in two subjects; the score completely normalized in 48 (50%) individuals]. BMI SDS reduction was a unique predictor of the decrease of TSH, thyroid volume, and structure, whereas CRPhs reduction was an independent predictor only for the TSH change. Moreover, CRPhs variations mediated the association between BMI SDS and TSH. The alterations of thyroid function and structure in children with obesity are reversible after weight loss.