Characteristics of Serum Thyroid Hormones in Different Metabolic Phenotypes of Obesity

Abstract

Aim: Metabolically healthy obese (MHO) individuals have attracted broad attention. We aimed to investigate the characteristics of serum thyroid hormones in different metabolic phenotypes of obesity. Methods: The study included 1,023 community-based euthyroid subjects (age range: 27-81 years), of whom 586 were women. Fat% was detected by a bioelectrical impedance analyzer. Two definitions of obesity were applied as follows: (1) fat% ≥ 25% for men and ≥ 30% for women; (2) body mass index (BMI) ≥ 25 kg/m 2. According to the diagnostic criteria for metabolic syndrome by the Chinese Diabetes Society, metabolically unhealthy was defined as two or more components of metabolic syndrome, excluding waist circumference. Serum-free triiodothyronine (FT3), free thyroxine (FT4), and thyroid-stimulating hormone (TSH) levels were measured by electrochemiluminescence immunoassay. Results: The proportions of obesity defined by fat% and BMI were 41.3 and 27.1%, respectively. The proportion of metabolically unhealthy was 41.6%. After adjusting for age and gender, regardless of the definitions based on fat% or BMI, FT3 was positively related to both the MHO and the metabolically unhealthy obese (MUO) phenotypes [MHO: odds ratio (OR)s = 1.676 based on fat% and 2.055 based on BMI; MUO: ORs = 1.818 based on fat% and 1.526 based on BMI; all P < 0.05]; FT4 was negatively related to the MUO phenotype (ORs = 0.870 based on fat% and 0.849 based on BMI, all P < 0.05); FT3/FT4 was also positively related to both the MHO and the MUO phenotypes (MHO: ORs = 1.678 based on fat% and 2.825 based on BMI; MUO: ORs = 2.866 based on fat% and 2.883 based on BMI; all P < 0.05); and TSH was positively related to the metabolically unhealthy non-obese phenotype (ORs = 1.329 based on fat% and 1.321 based on BMI, all P < 0.01). Conclusions: In euthyroid population, both the MHO and the MUO phenotypes were characterized by increased FT3 and FT3/FT4 levels.

Association between different obesity phenotypes and hypothyroidism: a study based on a longitudinal health management cohort

“…To the best of our knowledge, this is the first cohort study investigating the association between different obesity phenotypes and the incidence of hypothyroidism focusing on sex and age differences. A few previous studies have investigated the relationship between thyroid function within the reference range and different obesity phenotypes [ 18 – 20 ]. As there are no universally accepted criteria of obesity phenotypes, we adopted the definition previously used in the Chinese population [ 20 ].…”

“…According to the diagnostic criteria for metabolic syndrome of the Chinese Diabetes Society [ 24 ], metabolically unhealthy was defined as having at least two of the following four metabolic syndrome components: (1) fasting plasma glucose (FPG) ≥ 6.1 mmol/L; (2) systolic blood pressure (SBP) ≥ 130 mmHg or diastolic blood pressure (DBP) ≥ 85 mmHg; (3) triglycerides (TGs) ≥ 1.7 mmol/L; and (4) high-density lipoprotein cholesterol (HDL-C) < 1.0 mmol/L. Waist circumference was excluded from the definitions of metabolically unhealthy status due to its high multicollinearity with BMI [ 20 ]. According to their obesity and metabolic statuses, individuals were classified into four different obesity phenotypes: (1) metabolically healthy nonobese (MHNO): BMI < 25 kg/m 2 and fewer than two metabolic syndrome components; (2) MHO: BMI ≥ 25 kg/m 2 and fewer than two metabolic syndrome components; (3) MUNO: BMI < 25 kg/m 2 and at least two metabolic syndrome components; and (4) metabolically unhealthy obese (MUO): BMI ≥ 25 kg/m 2 and at least two metabolic syndrome components.…”

“…Only a few previous studies have investigated whether thyroid function could identify obesity phenotypes in euthyroid subjects [ 17 – 20 ]. However, no cohort studies have investigated the relationship between different obesity phenotypes and the development of hypothyroidism.…”

Взаимосвязь Между Ожирением И Уровнем Тиреотропного Гормона У Взрослых

“…Figures published by the World Health Organization show that the global prevalence of obesity has risen approximately three-fold in the 45-year-period since 1975 [1]. The condition has been linked to complications such as insulin resistance, hypertension, systemic inflammation, type 2 diabetes mellitus, cardiovascular diseases, and cancer [2]. Obesity is also associated with numerous endocrine abnormalities, including thyroid dysfunction and central obesity.…”

No Association between Neck Circumference and Free Triiodothyronine in Euthyroid Men

“…yroid hormone has been regarded as a regulator of body weight and metabolic status due to its physiological action in regulating energy homeostasis, thermogenesis, oxygen consumption, and glycolipid metabolism [5][6][7][8]. Studies have shown that thyroid hormones are significantly correlated with BMI, WC, and other indicators that determine weight status or body fat distribution and metabolic parameters such as lipid profiles, blood pressure, and blood glucose [9][10][11][12].…”