Thyroid-Stimulating Hormone, Triiodotyronine and Thyroxine Concentrations and Their Relationship with Metabolic Parameters, Anthropometric Variables and Body Composition in Premenopausal Euthyroid Obese Women

Purpose: This study was performed to evaluate the potential relationships of thyroid hormones, metabolic parameters, and anthropometric variables with body composition in premenopausal women. Material and Method: A total of 84 women with a mean age of 35.12+/-8.11 years were investigated. Subjects with a history of diabetes, hyperthyroidism and hypothyroidism, chronic liver, and renal disease were excluded from the study. In all subjects, anthropometric parameters were evaluated and body composition was analyzed by bioelectrical impedance analysis (BIA). Fasting serum thyroid-stimulating hormone (TSH), triiodothyrionine (T3), thyroxine (T4), fasting blood glucose (FBG), total cholesterol (TC), triglyceride (TG), high-density lipoprotein cholesterol (HDL-C), C-reactive protein (CRP), and interleukin 6 (IL-6) were measured by enzymatic methods. Serum low-density lipoprotein cholesterol (LDL-C) was determined by Friedewald formula. Results: Serum TSH, CRP and TC levels in obese subjects were significantly higher than in non-obese subjects (p<0.05). Serum TSH concentration was positively associated with waist to hip ratio (WHR) and fat mass and, negatively associated with fat-free mass (p<0.05). There was also a positive relationship between T3 and TG and between T4 and LDL-C in all participants. In comparison of subjects with different body fat percentage, subjects with higher body fat had also higher amount of TSH concentrations (p=0.015). Discussion: Our results showed a relationship of fat mass and lipid profile with thyroid function in premenopausal women. Further researches are needed to clarify the nature and mechanism of these relationships.