Thyroid Function in Obese Patients without Thyroid Disorders

Abstract

Background: Thyroid status influences weight and thyroid function is altered in obese individuals. Objective: This study aimed to see the levels of free thyroxine (FT4) and thyroid-stimulating hormone (TSH) and their relationship with the parameters of obesity in obese children and adults with primary exogenous obesity without thyroid disorders. Materials and Methods: This retrospective cross-sectional study was done in the Department of Endocrinology, Bangabandhu Sheikh Mujib Medical University, from May 2019 to March 2020 in 238 children and adults with primary exogenous obesity. Individuals with thyroid disorders were excluded from the study. Data were taken from hospital records to assess the thyroid function (FT4 and TSH) in obesity. Results: Two hundred and thirty-eight individuals with a mean age of 16.42 ± 9.72 years (range 3–62 years) and mean body mass index of 31.09 ± 7.64 kg/m2 were included in the study. The distribution of FT4 was normal and that of TSH was skewed to the right. Ninety-five percent confidence interval (CI) of FT4 and TSH was within the normal reference range. Ninety-five percent CI of FT4 was in the upper end of normal (1.176–1.251 mIU/L in ≤20 years and 1.094–1.306 mIU/L in >20 years) and that of TSH was in the lower end of normal (2.619–3.207 mIU/L in ≤20 years and 2.616–4.141 mIU/L in >20 years). About 13.4% had low FT4 and 15.4% had raised TSH. Waist circumference (WC) had a negative linear association with FT4 (r = −0.229, P = 0.003, R 2 = 5.24%), which was not present in the multivariate analysis. WC was significantly higher in the first versus third quartile of FT4 (103.974 ± 17.211 vs. 94.818 ± 14.544 cm). Conclusion: FT4 and TSH levels were in the lower and upper end of normal, respectively, in obese patients without thyroid disorders. Central obesity was negatively associated with FT4 in obese individuals.