THE RELATIONSHIP BETWEEN SERUM THYROID-STIMULATING HORMONE, INSULIN RESISTANCE, AND CARDIOVASCULAR RISK FACTORS IN OBESE PATIENTS WITH SUBCLINICAL HYPOTHYROIDISM

Background. The epidemic of overweight and obesity presents a major challenge to chronic disease prevention and health across the life course around the world. The putative relationships between thyroid hormones, body weight, and adipose tissue homeostasis have been the focus of several studies in recent years, but the causal relationships between these parameters have not been well established. The purpose of the study: to investigate the relationship between serum thyroid-stimulating hormone (TSH), insulin resistance (IR), and cardiovascular risk factors in a sample of obese people with subclinical hypothyroidism. Materials and methods. A retrospective, longitudinal analysis of 145 obese patients was performed. The TSH and free thyroxine (fT4) levels, anthropometric measurements, and laboratory test results were analyzed. Results. Twenty-three individuals presented with TSH levels above the normal level (subclinical hypothyroidism). Their waist circumference (WC) was significantly higher than that of euthyroid individuals. Serum TSH positively correlated with the homeostasis model assessment of insulin resistance (HOMA-IR) index, triglycerides, and high-density lipoprotein cholesterol (HDL-C). Using TSH and body mass index as independent variables, TSH levels were shown to be independently related to HOMA-IR (p = 0.002) and triglycerides (p = 0.006). Among euthyroid subjects, individuals with TSH values < 2.5 mIU/ml exhibited statistically significant decreases in waist-to-hip ratio, HDL-C levels, and HOMA-IR scores and a tendency toward lower WC values. Conclusions. Subclinical hypothyroidism in overweight and obese people appears to be associated with excess weight, especially visceral weight. In the present sample of obese patients, TSH levels appear to be associated with insulin resistance.