Obesity is associated with increased serum TSH level, independent of thyroid function

Association of Thyroid Function With Lipid Profile in Patients With Metabolic Syndrome: A Prospective Cross-Sectional Study in the Indian Population

Introduction Metabolic syndrome is a group of aberrant metabolic indicators including hypertension, dyslipidemia, impaired fasting blood glucose, and obesity. It has been reported that thyroid hormones have a strong influence on the cardiovascular system, and hypothyroidism has been linked to metabolic syndrome components. The objective of the study was to find out the association of thyroid function with lipid profile in patients with metabolic syndrome. Methods A prospective cross-sectional study was conducted in an apparently healthy adult population visiting the outpatient Department of Indira Gandhi Institute of Medical Sciences (IGIMS), Patna, Bihar, India. Metabolic syndrome was diagnosed according to the International Diabetes Federation (IDF) criteria. Fasting blood glucose, triglyceride, and HDL levels were tested using the enzymatic photometric method. Thyroid-stimulating hormone (TSH), free T4, free T3, and insulin assays were performed using chemiluminescence immunoassay (CLIA). Results Out of 197 subjects recruited, 86 (51 males and 35 females) were diagnosed with metabolic syndrome according to the IDF criteria, and the rest 111 without metabolic syndrome were considered to be the controls. The mean age of subjects with and without metabolic syndrome was 45.8±8.5 and 46.4±9.6 years, respectively. The prevalence of thyroid dysfunction in the present study was 22%. In subjects with metabolic syndrome, most of the clinical and hormonal parameters (waist circumference, waist-height ratio, fasting blood sugar, fasting insulin, triglycerides, T3, and TSH) were significantly higher (p<0.001) as compared to those without metabolic syndrome. In case of lipid profile, the triglycerides in those with metabolic syndrome (262.8±112.3 mg/dL) were significantly higher (p<0.001) than those without metabolic syndrome (137.9±19.01 mg/dL), while the serum levels of HDL were significantly higher (p<0.001) in group without metabolic syndrome (50.5±3.9 mg/dL) as compared to those with metabolic syndrome (43.4±5.2 mg/dL). Also, the TSH levels were significantly higher (p<0.001) in subjects with metabolic syndrome (5.3±3.4 μl/mL) as compared to those without metabolic syndrome (2.6±1.4 μl/mL). Among all the components of metabolic syndrome, waist circumference and HDL showed a significant strong positive correlation (r=0.51) with TSH, and systolic blood pressure (r=0.39), diastolic blood pressure (r=0.39), and fasting blood sugar levels (r=0.44) showed significantly moderate positive correlation with TSH levels. T4 (OR=8.82; 95% CI: 1.56-49.8) and TSH (OR=1.61; 95% CI: 1.19-2.18) levels were observed to have significantly higher odds as risk factors for metabolic syndrome. Conclusion There is a significant association of thyroid function with lipid profile in metabolic syndrome. It was observed that along with metabolic alterations, cardiovascular symptoms of hypothyroidism and subclinical hypothyroidism are possible. Therefore, while evaluating people with metabolic syndrome, it may be appropriate to look into how well their thyroid glands are functioning.

Thyroid axis hormones and anthropometric recovery of children/adolescents with overweight/obesity: A scoping review

Introduction

Thyroid hormones exert multiple physiological effects essential to the maintenance of basal metabolic rate (BMR), adaptive thermogenesis, fat metabolism, growth, and appetite. The links between obesity and the hormones of the thyroid axis, i.e., triiodothyronine (T3), thyroxine (T4), and thyrotropin (TSH), are still controversial, especially when considering children and adolescents. This population has high rates of overweight and obesity and several treatment approaches, including nutritional, psychological, and physical exercise interventions have been used. Understanding the importance of the hormones of the thyroid axis in the recovery from overweight and obesity may help directing measures to the maintenance of a healthy body composition. The present scoping review was carried out to analyze studies evaluating these hormonal levels throughout interventions directed at treating overweight and obesity in children and adolescents. The main purpose was to ascertain whether the hormones levels vary during weight loss.

Methods

We selected for analysis 19 studies published between 1999 and 2022.

Results

Most of the studies showed that changes in different anthropometric indicators, in response to the multidisciplinary interventions, correlated positively with free T3 (fT3), total T3 (TT3), and TSH. With respect to free T4 (fT4) and total T4 (TT4).

Discussion

The most common finding was of unchanged levels and, hence, no significant association with weight loss. Moreover, thyroxine supplementation has failed to affect the response to the interventions. Further studies are necessary to elucidate the relevance of the variations in hormone levels to the establishment of overweight/obesity and to the recovery from these conditions in children/adolescents.

Systematic review registration

https://www.crd.york.ac.uk/prospero/, identifier CRD42020203359.

New Anthropometric Measurements: Relationship to Thyroid Functions in Euthyroid Obese Subjects

Introduction

Body mass index (BMI) is unable to make a distinction between muscle mass and fat mass. Therefore, new anthropometric measurements, such as a body shape index (ABSI), body round index (BRI), and body adiposity index (BAI), have been formulated in recent years. Many studies have reported a correlation between BMI and thyroid function. In this study, we aimed to investigate the relationship between the above-mentioned new anthropometric measurements and thyroid functions in euthyroid obese subjects.

Methods

We included 675 euthyroid (TSH ≥ 0.4 and < 4.5 mIU/l) individuals from the obesity outpatient clinic, aged between 18 and 65 years old, with BMI ≥ 30. Thyroid-stimulating hormone (TSH), free T4 (fT4) and free T3 (fT3), anthropometric measurements (weight, height, and waist circumference), and bioelectric impedance analyses [percent body fat (PBF) and fat-free mass (FFM)] of individuals were measured and recorded. ABSI, BRI, and BAI were calculated with the data from these measurements. Anthropometric measurements were compared to thyroid function tests.

Results

Eighty percent of the subjects were female. The mean age and BMI were 38 ± 17 years and 38 ± 6 kg/m², respectively. TSH was found to be negatively correlated with ABSI (p = 0.006) and positively correlated with BAI (p < 0.001), but a statistically significant relationship with BRI (p = 0.193) was not determined. Free T4 was not associated with any of the anthropometric measurements.While fT3 was determined to be positively correlated with ABSI (p = 0.008) and negatively correlated with PBF and BAI (p = 0.001, p = 0.002, respectively), no statistically significant relationship with fT3 and BRI was determined.

Conclusion

TSH is positively correlated with measurements of adiposity such as BMI, PBF, BAI while indexes in which abdominal obesity increases, such as waist circumference (WC), waist-hip ratio (WHR), and ABSI, are correlated with fT3 levels.