Evaluation of relationship irisin levels patients with subclinical hyperthyroidisim and clinical hyperthyroidism

Objective: Energy expenditure effects and role on the thermogenesis of thyroid hormones are well known. In this regard various mechanisms are defined. In recent years, a novel myokine that plays important role on energy expenditure, insulin resistance and thermogenesis has been discovered. Irisin is an exercise-induced hormone secreted by skeletal muscle in mice and humans that drives brown-fat-like conversion ofwhite adipose tissue, which is defined as the occurrence of thermogenic brown adipocytes in white adipose tissue, and that improves systemic metabolism by increasing energy expenditure. In this study we aimed to investigate relationship between two hormones that have similar effects on energy metabolism and thermogenesis, each other and on insulin resistance. Method: Our study was designed as case-control research. Thirty two patients who admitted Dokuz Eylul University School of Medicine Endocrinology outpatient clinic between the dates of December 2012 and June 2013 with a new diagnosis of subclinical hyperthyroidism and 32 healthy individuals who had a similar age range and similar demographic characteristics were enrolled. Although 3 patients have clinical hyperthyroidism, they didn't admitted to research because of their minority. At fasting stated glucose, irisin, insuline, C-peptid, thyroid function tests were studied. Also HOMA-IR and QUICKI-IS tests used to calculate insuline resistance and sensivity. Findings: There were not difference on age, height and BMI between two groups that were included in the research. There were not significant correlation between irisin levels and fT3, fT4, TSH, HOMA-IR, QUICKI-IS. There were positive correlation between age and BMI. Results:There were not significant correlation between irisin levels and fT3, fT4, TSH, HOMA-IR, QUICKI-IS. These two hormones probably independently show their effects on energy enpenditure and thermogenesis. We need further studies with more patients and clinical hyperthyroidism group. Key Words: Subclinical hyperthyroidism, irisin, insulin resistance