Endocrine Abstracts

Introduction

Obesity is an important medical and social problem of our time, because its prevalence is growing rapidly and affects about 30% of the adult population of the planet. Obesity is characterized by an increase in the expression of cytokines that cause endothelial damage. It is known that prohormone thyroxine (T₄) is converted into 5 times more active triiodothyronine (T₃) in peripheral organs (such as liver kidneys) and tissues with the help of deiodinases. Hyperproduction of cytokines by adipose tissue impairs this conversion of thyroid hormones with the development of ’low T₃’ syndrome. Besides adequate blood supply is important in the process of deiodination of T₄. Therefore, it is important to study the relationship between endothelial function and thyroid hormones metabolism.

The aim of the study

To study the dependence of thyroid hormones metabolism on the level of vascular endothelial growth factor in the serum of venous blood in obese patients.

Materials and methods

52 obese patients and 20 practically healthy persons were enrolled into the study. Obesity was established in the case of an increase in body mass index above 30 kg/m². Free triiodothyronine (fT₃) and free thyroxine (fT₄) levels were determined. To assess the violation of peripheral conversion of thyroid hormones, the ratio of fT₃/fT₄ was calculated. The level of vascular endothelial growth factor (VEGF) was determined.

Results

In obese persons, a decrease in fT₃ by 31.4%, an increase in fT₄ by 22.6% and decrease in fT₃/fT₄ ratio by 39.1% (P < 0.05) were found. An increase in VEGF expression by 37.3% on the background of obesity compared with control (P < 0.05) were revealed. Negative correlations between VEGF expression and fT₃ (r = –0.438, P < 0.05), fT₃/fT₄ (r = –0.522, P < 0.05) were obtained.

Conclusions

1. Metabolism of thyroid hormones is decreased with the development of the syndrome of ’low triiodothyronine syndrome’ in obese patients. 2. Endothelial function is impaired with increasing expression of vascular endothelial growth factor against the background of obesity, 3. Indicators of thyroid hormone metabolism depend on the level of vascular endothelial growth factor.