Evaluation of the relationship between epicardial adipose tissue, omentin-1 levels, atherosclerosis markers and body composition in hypothyroidism

It is known that patients with hypothyroidism gain weight but the factors (increase in adipose tissue or water-salt uptake) responsible for this increase is controversial. In order to determine which factor is responsible for weight gain, we aimed to investigate body composition changes in our patients. Furthermore epicardial adipose tissue thickness, serum omentin-1 and H-FABP, some risk factors and indicators for coronary atherosclerosis (hsCRP, homocysteine, CIMT, FMD, etc) were examined both pre and post treatment in hypothyroid patients and compared with euthyroid healty control group. For this purpose, 28 newly diagnosed overt hypothyroid patients and the age, sex and body mass index matched control group of 28 healthy euthyroid volunteers were examined. The hypothyroid group were evaluated before the treatment and 6 months after replacement therapy when they were euthyroid for at least two visit. Body composition was measured by dual energy x-ray absorptiometry and epicardial adipose tissue thickness was measured by transthoracic echocardiography. Serum Omentin-1 and H-FABP levels were studied on the principle of sandwich ELISA. Other hematological parameters were measured by standard laboratory methods. Six months after replacement therapy, body weight and body mass index were decreased in patients with overt hypothyroidism. The decrease in lean body mass (not adipose tissue mass) were found to be responsible for this reduction. Increased glomerular filtration rate and free water clearance, with the correction of hypothyroidism, can be considered as a reason to explain it. In hypothyroid patients, epicardial adipose tissue thickness was higher than the healty control group and significantly decreased 6 months after replacement therapy. Serum omentin-1 levels were lower than the healthy control group. However serum omentin-1 levels were found to be increased and reached the similar level with the control group 6 months after the replacement therapy. H-FABP levels showed no difference after treatment as well as with healty control group. In our study, free T4 level was found to be an independent factor to predict epicardial adipose tissue thickness in overt hypothyroid patients. In addition to well-known pathways, increased the amount of epicardial adipose tissue and decreased serum omentin-1 levels can be considered as a factor responsible for the pathogenesis of atherosclerosis in hypothyroidism.