Relationship between Body Mass Index, Waist-to-Hip Ratio, and Serum Lipid Concentrations and Thyroid-Stimulating Hormone in the Euthyroid Adult Population

The aim of this cross-sectional study was to investigate the relationship between body mass index (BMI), waist-to-hip ratio, and lipid parameters and serum thyroid-stimulating hormone (TSH) levels in healthy euthyroid individuals. This cross-sectional study was conducted between June 1(st) and July 20(th), 2013, at Bushehr University of Medical Sciences. One hundred forty euthyroid individuals were divided into 2 groups: a high-TSH group (TSH between 2.0 and 5.5 mIU/L, n=67) and a low-TSH group (TSH between 0.3 and 2.0 mIU/L, n=73). After overnight fast, total cholesterol, triglyceride (TG), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), TSH, thyroxine (T4), and triiodothyronine (T3) were measured. Height and weight were measured with a stadiometer, and BMI was calculated as weight in kilograms divided by the square of height in meters. Waist-to-hip ratio was determined as waist circumference divided by hip circumference. The simple independent t-test and a general linear model were used for statistical analysis. All statistical analyses were done using the SPSS, version 15, statistical software package. BMI and LDL-C were significantly higher in the high-TSH group than in the low-TSH group after adjustment for age, sex, calorie intake, total fat and carbohydrate intakes, and physical activity. No significant differences were found between the groups in TG, cholesterol, and HDL-C. The association between TSH levels andT4 was significant. Individuals with TSH levels at the upper limit of normality might be at risk of hypercholesterolemia and obesity.