Endocrine Abstracts

Introduction: Irisin is a myokin secreted by myocytes responsible for transmission of signals from muscles to other body tissues. It improves systemic metabolism by increasing energy expenditure and has a significant influence on the body metabolism and thermogenesis. Thyroid disorders are characterized by a disrupted thermo-metabolic state and muscular damage, and the underlying mechanisms still not clear.

Aim: To evaluate serum Irisin levels in patient with hypothyroid and hyperthyroid disease and its relation to creatinine kinase (CK) a marker of muscle damage.

Method: 90 subjects participated in the study. They were divided into three groups: Group 1: 30 hyperthyroid patients, Group 2: 30 hypothyroid patients, Group 3: 30 normal persons. They were submitted to history, medical examination (Weight, Height and BMI) and measurement of fasting serum Irisin, TSH, Free T₃, Free T₄, CK.

Results: Irisin hormone level was lower in hypothyroid patients (16.60±4.07) Pg/ml than hyperthyroid patients (26.83±7.95) Pg/ml and controls (25.70±5.29) Pg/ml (P<0.01). However, it was higher in hyperthyroid than (P>0.05). Creatine kinase (CK) level decreased in hyperthyroid patients (33.80±1.49) μ/l than hypothyroid patients (196.26±4.53) μ/l and controls (62.86±1.63) μ/l (P<0.01). However, creatine kinase increased in hypothyroid patients (196.26±4.53) μ/l in comparison with control (62.86±1.63) μ/l (P<0.01). There is a negative correlation between Irisin, TSH, Weight, BMI and CK (P<0.01), and a positive correlation with freeT₃ and free T4 (P<0.01) in hyperthyroid patients.

Conclusion: Lower Irisin hormone level was found in patients with hypothyroidism which might be explained by muscles destruction demonstrated with high CK levels, however the higher level of Irisin in hyperthyroidism might explained by hypermetabolic state.