ABSTRACT

OBJECTIVE: An association between obesity and thyroid function has mostly been investigated in adult subjects. Fewer studies have been performed to investigate the effect of excessive obesity on the thyroidal axis in children and have led to conflicting observations. In this study we have evaluated the thyroid function in children with monogenic obesityby measuring serum thyroid stimulating hormone (TSH), triiodothyronine (T3) and thyroxine (T4). In addition we have determined serum leptin concentrations in the study subjects. MATERIALS AND METHODS: The present study was carried out in 27 children with severe early onset obesity (BMI SDS>3.5) due to known loss-of-function mutations in the leptin (LEP), leptin receptor (LEPR) or melanocortin 4 receptor (MC4R) gene. In addition 13 age-matched normalweight subjects negative for these mutations served as the control group. Serum TSH, T3, T4, and leptin were analyzed by using commercially available kits. RESULTS: Remarkably, the circulating TSH, T3 and T4 were found to be within the normal range in all the 3 groups of children with severe obesity and the values of these hormones were not significantly different from those of the control group. As expected, leptin levels were non-detectable in children with LEP mutations, and were raised over the reference values in subjects with LEPR or MC4R deficiency. CONCLUSION: The present study fails to establish an association of thyroid function with excessive adiposity in children due to monogenic causality. More importantly, complete leptin deficiency or a disruption of the leptin downstream signaling appears to have little effect on TSH or thyroid hormone secretions. However, there remains the possibility that any adverse effects of adiposity on pituitary-thyroid axis as reported in some studies, may arise due to other obesity associated metabolic dysfunctions becoming apparent at a later stage of life. Keywords: Monogenic obesity; Thyrotropin; Thyroid hormones; Leptin

https://ijbpas.com/pdf/2019/July/MS_IJBPAS_2019_4761.pdf

Download PDF
https://doi.org/10.31032/IJBPAS/2019/8.7.4761