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Abstract
Background and Aim: Irisin is a newly identified myokine secreted by skeletal muscle and has significant effects on body metabolism. Thyroidal functional state has a profound influence on the metabolism of human body. Therefore. the aim of this study was to investigate the possible changes in serum irisin concentrations before and after treatment in hypothyroid subjects.
Methods: The study included 26 patients with overt hypothyroidism due to Hashimoto thyroiditis and 19 healthy subjects. Baseline serum thyroid function tests. presence of thyroid autoantibodies and levels of creatine kinase (CK) and irisin were measured in both groups. All measurements in the hypothyroid group were repeated after euthyroidism was achieved.
Results: Serum irisin levels were significantly lower in the hypothyroid groups than the control group (p<0.001). Negative correlation between irisin and TSH and CK levels (r=-0.623. p<0.001. r:-0.389. p:0.008. respectively) and a positive correlation between irisin and fT4 levels (r:0.570. p<0.001) was found. Serum CK levels decreased significantly after treatment(p<0.001).Serum irisin levels significantly increased (from 57.4 U/L to 99.8U/L. p<0.001) when the hypothyroid patients were treated to achieve euthyroidism.
Conclusions: To the best of our knowledge this is the first study providing insight that low serum irisin levels significantly increased following treatment to euthyroid state in overt hypothyroid patients with Hashimoto thyroiditis. The negative correlation between CK and irisin levels found in our study might underline a possible relation between irisin level and muscle damage in patients with hypothyroidism due to Hashimoto’s thyroiditis. The increase in irisin levels and the decrease in CK levels after treatment may indicate myopathy due to hypothyroidism. Larger scale studies are needed to confirm these results and to ensure irisin as a possible biomarker of Hashimoto’s thyroiditis.